SNData

SNData provides access to data releases published by a variety of supernova (SN) surveys. It is designed to support the development of scalable analysis pipelines that translate with minimal effort between and across data sets. A summary of accessible data is provided below. Access to additional surveys is added upon request or as needed for individual research projects undertaken by the developers. To request an additional survey / data release, please raise an issue on GitHub.

Using These Docs

SNData is designed to provide as consistent of an interface as possible across surveys. The Getting Started guides are intended to help you get up and running quickly and to familiarize you with the general SNData interface. Additional API documentation is provided for each individual data set to highlight any (very) minor deviations a particular survey or data release may have from the rest of the package. In general you should:

1. Read the installation guide (~1 minute if you know how to use pip)
2. Read the quick start guide to learn how the package works (~5 minutes)
3. Read the slow start guide for a better understanding of the available features and how they can make your life easier (~10 minutes)
4. Refer to the API documentation for a given survey as you see necessary

Available Data

SNData provides data access for the following supernova surveys. If you are having issues downloading data for a particular survey or data release, please check the Server Status Page.

Survey Name	Data Release	Data Type
Carnegie Supernova Project	DR1	Spectroscopic
	DR3	Photometric
Dark Energy Survey	SN3YR	Photometric
Equation of State: Supernovae Trace Cosmic Expansion	Narayan et al. 2016	Photometric
Joint Light-Curve Analysis	Betoule et al. 2014	Photometric
Lick Observatory Supernova Search	Ganeshalingam et al. 2013	Photometric
Sloan Digital Sky Survey	Sako et al. 2018	Photometric
	Sako et al. 2018	Photometric
Supernova Legacy Survey	Balland et al. 2009	Spectroscopic
Sweetspot	Weyant et al. 2018	Photometric

Change Log

This page documents any API changes between different versions of the sndata package.

V 1.2.2

• Introduces the abstract sndata.base_classes.Base
• Logic from the sndata.utils module is moved into multiple sub-modules.
• Increases required numpy version to >= 1.17.0

V 1.2.1

• Patches missing file bug for Ganeshalingam et al. 2013 release.
• Hides any benign warnings when parsing data files.

V 1.2.0

• Adds data from the first data release of the BLick Observatory Supernova Search (sndata.loss.Ganeshalingam13).
• The format argument is added to the utils.convert_to_jd function.
• Support is added to utils.convert_to_jd for converting UT times to JD.

V 1.1.1

• Fixes bug where existing data is not skipped during download by default.

V 1.1.0

• Adds data from the first data release of the Sweetspot survey (sndata.sweetsport.DR1).

V 1.0.1

• For consistency with the rest of the package, time values in data tables returned by the sndata.sdss.Sako18Spec class have been converted from UNIX timestamps to Julian day.

Installation and Setup

To install the package, please choose from one of the options below.

Note

No survey data is downloaded when installing or upgrading SNData. All data management is handled explicitly, as outlined in the Slow Start tutorial.

Using PIP (Recommended)

To install using the pip package manager, run:

pip install sndata

Pip will automatically install any missing dependencies in your Python environment. If you have any issues installing the package, try installing the dependencies manually and then reinstall sndata.

A list of required dependencies is provided on GitHub via a requirements.txt document. Dependencies can be installed by running:

# Clone the source code from GitHub
git clone http://github.com/djperrefort/SNData SNData

# Install dependencies
pip install -r SNData/requirements.txt

Using setup.py

If pip is unavailable on your system, the package source code is available on GitHub.

# Clone the source code from GitHub
git clone http://github.com/djperrefort/SNData SNData

# Install the package from source
cd SNData
python setup.py install --user

As in the previous method, any missing dependencies in your Python environment should be installed automatically. If you have any issues installing the package, install each dependency from requirements.txt and then try again.

Configuring Data Storage

By default data downloaded by sndata is stored in the installation directory. This can be changed to a custom directory by specifying the value SNDATA_DIR in your environment (i.e., in you .bash_profile or .bashrc file). For example:

export SNDATA_DIR="/your/data/directory/path"

Quick Start

The following is provided as a short example on how to import a supernova data release, download the corresponding data, and read it into memory. For a more in depth overview, see the Slow Start.

# All data releases are available as ``sndata.<survey name>.<release name>``
from sndata.csp import DR3

# Start by creating an instance of the data release
dr3 = DR3()

# Use ``help`` to get a description of the survey
print(help(dr3))

# Download data to your machine.
# Note: If data is already downloaded, this function call won't do anything.
dr3.download_module_data()

# Check what tables are available from the release's corresponding publication
published_tables = dr3.get_available_tables()
print(published_tables)

# Read one of those tables by referencing the table name or number
dr3_demo_table = dr3.load_table(published_tables[0])

# Check what objects are included in the data release
object_ids = dr3.get_available_ids()
print(obj_ids)

# Read in the data for an object using it's Id
demo_id = object_ids[0]
dr3.get_data_for_id(demo_id)

# Data is auto-formatted to be compatible with the SNCosmo package.
# To disable this and return data as presented on the data release,
# set ``format_table=False``.
dr3.get_data_for_id(demo_id, format_table=False)

# For convenience you can iterate over all tables
data_iterator = dr3.iter_data()
for data in data_iterator:
    print('The first data table:')
    print(data)
    break

Slow Start

The following is provided as an in depth demonstration of the various functionality available in SNData. For more information on a specific module, please see that module’s page in the API documentation.

Importing a Survey

To access data from a specific survey, import it from the parent package. A summary of each data release, including any deviations from the standard UI, can be accessed by calling the builtin help function. For demonstration purposes we will be using the third data release from the Carnegie Supernova Project.

from sndata.csp import DR3

# At instantiation, the DR3 class determines where the data
# is located on your machine
dr3 = DR3()

# Information about the parent survey
print(dr3.survey_name)
print(dr3.survey_abbrev)

# A summary of the DR3 data set
help(dr3)

# Where to go for more information
print(dr3.survey_url)

# The type of data in this release
print(dr3.data_type)

# The primary publication(s) and NASA ADS link(s) describing the data
print(dr3.publications)
print(dr3.ads_url)

# Photometric data releases include filters
print(dr3.band_names)

Downloading Data

To minimize disk space usage, SNData does not come pre-installed with any survey data. Instead, users must manually tell SNData to download (or delete) data from their local machine.

# Get an overview of the provided data
help(dr3)

# Download data for the given survey / data release
dr3.download_module_data()

# Delete any downloaded data for the given survey / data release
dr3.delete_module_data()

It is useful to note that any data has already been downloaded is skipped over by download_module_data, making it safe to call in an automated pipeline environment. This behavior can be disabled by specifying the force=True argument.

Important

Survey data is often hosted across multiple websites. As such, it is possible the server responsible for hosting a subset of a survey’s data (e.g. the filter transmission curves) is temporarily offline. In this case SNData will raise a warning and continue downloading any data that is still online. The download_module_data function can then be re-run once the server is back online.

Accessing Data

Observational data can be retrieved for individual objects as astropy tables. For convenience, the Ra, Dec, redshift, and redshift error are included in the table’s meta data when available.

# Get a list of available objects
list_of_ids = dr3.get_available_ids()

# Get data for a given object
demo_id = list_of_ids[0]
data_table = dr3.get_data_for_id(demo_id)
print(data_table)

# Don't forget to check the meta data!
print(data_table.meta)

Data tables returned by SNData are formatted for use with the sncosmo python package. In doing so, the values of the table may be manipulated from the original file data into different units, column names, etc. To disable this feature, specify the format_table=False argument.

The iter_data function is also provided for convenience to iterate over data for all available objects.

for data in dr3.iter_data():
    print(data)
    break

This function allows users to optionally select a subset of the total data by defining a filter function. This function should accept a data table yielded by iter_data and return a boolean. For example, to only select target with a redshift less than .1:

def filter_func(data_table):
    return data_table.meta['z'] < .1

for data in dr3.iter_data(filter_func=filter_func):
    print(data)
    break

Important

As iter_data iterates over supernovae, it reads in data from file for a given object before checking the filter function. For this reason, filter functions should not be used in an attempt improve runtime by reducing I/O operations as it will have no effect.

Reading Tables

Some surveys include summary tables in their data releases. The inclusion of tables from published papers is also common.

# Check what tables are available
published_tables = dr3.get_available_tables()
print(published_tables)

# Read one of those tables by referencing the table name or number
demo_table_name = published_tables[0]
demo_table = dr3.load_table(demo_table_name)

Note that the load_table function caches the returned result in memory. This improves the speed of successive calls and means you don’t have to be worried about I/O performance.

Registering Filters with SNCosmo

SNData automatically formats data for use with the SNCosmo package. To fully take advantage of this, SNData is also able to register the filter transmission curves for a given survey into the sncosmo registry (the registry is how SNCosmo keeps track of what each filter, model, etc. are called).

import sncosmo

# The names of the bands that will be registered
print(dr3.band_names)

# Register the band-passes of the survey with SNCosmo
# You can optionally specify ``force=True`` to re-register band-passes
dr3.register_filters()

# Get data for SN 2004dt
data_table = dr3.get_data_for_id('2004dt')
print(data_table)

# Fit the data
model = sncosmo.Model('salt2')
model.set(z=data_table.meta['z'])
result, fitted_model = sncosmo.fit_lc(
    data=data_table,
    model=model,
    vparam_names=['t0', 'x0', 'x1', 'c'])

print(result)

Combining Data Sets

SNData allows users to combine individual data releases into a single CombinedDataset object. The resulting object provides the same general user interface as a single data access module but provides access to data from multiple surveys / data releases.

Creating a Combined Data Set

To create a combined data set, import the data access classes for each of the data releases you want to join and pass them to the CombinedDataset object. For demonstration purposes we combine data from the third data release of the Carnegie Supernova Project and the three year cosmology release of the Dark Energy Survey:

 from sndata import CombinedDataset, csp, des

 combined_data = CombinedDataset(csp.DR3(), des.SN3YR())

The resulting object provides the same user interface as the rest of the SNData package, including having the same method names:

 # Download all data for the combined data releases
 combined_data.download_module_data()

 # Get a list of available supplementary tables
 list_of_table_ids = combined_data.get_available_tables()

 # Load a supplementary tables
 demo_table_id = list_of_table_ids[0]
 demo_sup_table = combined_data.load_table(demo_table_id)

 # Get a list of available objects
 list_of_ids = combined_data.get_available_ids()

 # Get data for a single object
 demo_id = list_of_ids[0]
 data_table = combined_data.get_data_for_id(demo_id)
 print(data_table)

 # Iterate over data for all objects in the combined data set
 for data in combined_data.iter_data():
     print(data)
     break

Important

The format of object and table Id’s for CombinedDataset objects is slightly different than for a single data release. Please keep reading.

Unlike the object and table Id’s for a single data release, the default Id’s for a CombinedDataset are tuples instead of strings. Each tuple contains three elements including (in order) the individual object identifier, data release name, and survey name. For example, the ID value for supernova ‘2007S’ from CSP Data Release 3 (DR3) would be ('2007S', 'DR3', 'CSP').

By specifying object Id’s in this way, it is ensured that objects in combined data releases always have unique identifiers. However, in the case where the object Id’s from two data releases are already unique (as is the case when combining csp.DR3` and ``des.SN3YR), CombinedDataset objects are smart enough to mimic the behavior of a normal / single data release and can take object Id’s as strings. For example:

# You can specify object ID's as tuples
combined_data.get_data_for_id(('2007S', 'DR3', 'CSP'))

# or if the object names across the joined surveys are unique, as a string
combined_data.get_data_for_id('2007S')

Joining Object Id’s

It is possible for two different photometric surveys to observe the same astronomical object. In this case, object Id’s from different surveys can be “joined” together so that when requesting data for a given object Id, data is returned for all Id’s that have been joined together. Accomplishing this is as simple as:

# Note that you can join an arbitrary number of object Id's
combined_data.join_ids(obj_id_1, obj_id_2, obj_id_3, ...)

# You can also retrieve a list of joined ID values
print(combined_data.get_joined_ids())

# To undo the above joining action
combined_data.separate_ids(obj_id_1, obj_id_2, obj_id_3, ...)

When retrieving data for a joined ID, the returned data table is simply the collective data tables for each joined ID stacked vertically.

data = combined_data.get_data_for_id(obj_id_1)
print(data)

It is worth noting that CombinedDataset objects are aware of successive join actions. This means that the following two examples are functionally equivalent.

# You can join multiple Id's at once ...
combined_data.join_ids(obj_id_1, obj_id_2, obj_id_3)

# Or join them successively
combined_data.join_ids(obj_id_1, obj_id_2)
combined_data.join_ids(obj_id_2, obj_id_3)

Creating Custom Data Classes

SNData uses an object oriented design to automate basic data management tasks and ensure a consistent user interface. Prebuilt template classes are provided to represent spectroscopic / photometric data, allowing users to create customized data access objects. In general, the steps for creating a new data access class include:

1. Inherit from one of the prebuilt SpectroscopicRelease or PhotometricRelease template classes
2. Define some meta data describing the data release
3. Define a few private functions for parsing your data set

Below we work through examples for photometric and spectroscopic data. If after working through these examples you still have remaining questions, please feel free to raise an issue on GitHub.

Spectroscopic Data

To create a data access class for spectroscopic data, we start by inheriting from the SpectroscopicRelease. We then add some meta data about the survey and data release that is being represented.

from sndata.base_classes import SpectroscopicRelease
from sndata import utils


# Class should be named to reflect the official acronym of the data release
# or, if an acronym is not available, the publication for the data
class Smith20(SpectroscopicRelease):
    """Describe the contents of the data release here
    (Source: Smith, Jhonson et al. 2020)

    Deviations from the standard UI:
        - None

    Cuts on returned data:
        - None
    """

    # General metadata
    survey_name = 'Demo Supernova Survey'  # Full survey name
    survey_abbrev = 'DSS'  # Official survey abbreviation
    release = 'Smith20'  # Name of the data release
    survey_url = 'www.url.com'  # URL of the official data release
    publications = ('Smith et al. 2020',)  # Any relevant publications

    # Link to ADS abstract of primary paper
    ads_url = 'https://ui.adsabs.harvard.edu/'

Next we use the __init__ method to define the local paths of the data being represented and, if desired, the remote URL’s the data should be downloaded from. All data should be stored in a subdirectory of the self._data_dir, which is determined automatically by SNData.

    def __init__(self):
        """Define local and remote paths of data"""

        # Call to parent class defines the self._data_dir attribute
        # All data should be downloaded to / read from that directory
        super().__init__()

        # Local data paths. You will likely have multiple directories here
        self._spectra_dir = self._data_dir / 'spectra_dir_name'

        # Define urls for remote data.
        self._spectra_url = 'www.my_supernova_spectra.com'

The logic for parsing individual data files is then added as private methods:

    def _get_available_tables(self) -> List[int]:
        """Get Ids for available vizier tables published by this data release"""

        # Find available tables - for example:
        # Find available tables - assume standard Vizier naming scheme
        table_nums = []
        for f in self._table_dir.rglob('table*.dat'):
            table_number = f.stem.lstrip('table')
            table_nums.append(int(table_number))

        return sorted(table_nums)

    def _load_table(self, table_id: int) -> Table:
        """Return a Vizier table published by this data release

        Args:
            table_id: The published table number or table name
        """

        readme_path = self._table_dir / 'ReadMe'
        table_path = self._table_dir / f'table{table_id}.dat'

        # Read data from file and add meta data from the readme
        data = ascii.read(str(table_path), format='cds', readme=str(readme_path))
        description = utils.parse_vizier_table_descriptions(readme_path)[table_id]
        data.meta['description'] = description
        return data

    def _get_available_ids(self) -> List[str]:
        """Return a list of target object IDs for the current survey"""

        # Returned object Ids should be sorted and unique.
        # For example:
        files = self._spectra_dir.glob('*.dat')
        return sorted(set(Path(f).name for f in files))

    def _get_data_for_id(self, obj_id: str, format_table: bool = True) -> Table:
        """Returns data for a given object ID

        Args:
            obj_id: The ID of the desired object
            format_table: Format for use with ``sncosmo`` (Default: True)

        Returns:
            An astropy table of data for the given ID
        """

        # Read in data for the object ID and return an astropy table
        pass

    def _download_module_data(self, force: bool = False, timeout: float = 15):
        """Download data for the current survey / data release

        Args:
            force: Re-Download locally available data
            timeout: Seconds before timeout for individual files/archives
        """

        # If you do not wish to include download functionality,
        # do not include this method

        # The ``utils`` module includes functions for downloading files
        # See the ``utils.download_tar`` and ``download_tar.download_file``
        # functions. Here is an example:
        utils.download_tar(
            url=self._spectra_url,
            out_dir=self._data_dir,
            skip_exists=self._spectra_dir,
            mode='r:gz',
            force=force,
            timeout=timeout
        )

Notice that there is no need to explicitly raise errors for invalid object Id’s (InvalidObjId) or handle errors where there is no downloaded data (NoDownloadedData). This is handled automatically by the SpectroscopicRelease class we inherited from.

Note

The formatting of Vizier tables is fairly standard, and there is a chance your _get_available_tables and _load_table methods be exactly the same as the above example. Instead of copy and pasting these two methods from above, you can alternatively inherit the DefaultDataParser class.

Photometric Data

Photometric data is represented the same way as spectroscopic data, but with a few differences. The first is to inherit from the PhotometricRelease class and to include a bit of extra meta data.

from sndata.base_classes import PhotometricRelease

class Smith20(PhotometricRelease):

    # Include all of the meta data for a spectroscopic data release and also
    # Specify the name and zero point of each photometric filter
    band_names = tuple('u', 'g', 'r', 'i', 'z')
    zero_point = tuple(25, 25, 25, 25, 25)

If not already using transmission filters built into sncosmo, you will also need to define the directory where the filter transmission curves are stored and add some small logic for registering those filters with sncosmo. For example:

    def __init__(self):
        """Define local and remote paths of data"""

        # Call to parent class defines the self._data_dir attribute
        # All data should be downloaded to / read from that directory
        super().__init__()

        # Local paths of filter transmission curves
        self._filter_dir = self.data_dir / 'filters'

    def _register_filters(self, force: bool = False):
        """Register filters for this survey / data release with SNCosmo

        Args:
            force: Re-register a band if already registered
        """

        bandpass_data = zip(self._filter_file_names, self.band_names)
        for _file_name, _band_name in bandpass_data:
            filter_path = self._filter_dir / _file_name
            wave, transmission = np.genfromtxt(filter_path).T
            band = sncosmo.Bandpass(wave, transmission)
            band.name = filter_name
            sncosmo.register(band, force=force)

Note

The _register_filters method shown above can also be inherited from the DefaultDataParser class.

Carnegie Supernova Project (CSP)

The csp module provides access to data from the Carnegie Supernova Project (CSP). It includes data from the first (DR1) and third (DR3) data releases.

Data Release	Class Name	Data Type	Publication
Data Release 1	DR1	Spectroscopic	Folatelli et al. 2013
Data Release 3	DR3	Photometric	Krisciunas et al. 2017

Data Release 1

class sndata.csp.DR1

The DR1 class provides access to spectra from the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project. It includes 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. (Source: Folatelli et al. 2013)

Important

The DR1 spectra are both published and returned by sndata in units of rest frame wavelength.

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

Data Release 3

class sndata.csp.DR3

The DR3 class provides access to data from the third data release of the Carnegie Supernova Project (CSP) which includes natural-system optical (ugriBV) and near-infrared (YJH) photometry of 134 supernovae (SNe) that were observed in 2004-2009 as part of the first stage of the Carnegie Supernova Project (CSP-I). The sample consists of 123 Type Ia SNe, 5 Type Iax SNe, 2 super-Chandrasekhar SN candidates, 2 Type Ia SNe interacting with circumstellar matter, and 2 SN 2006bt-like events. The redshifts of the objects range from z=0.0037 to 0.0835; the median redshift is 0.0241. For 120 (90%) of these SNe, near-infrared photometry was obtained. (Source: Krisciunas et al. 2017)

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

Dark Energy Survey (DES)

The des module provides access to data from the Dark Energy Survey (DES). It includes photometric data used in the cosmological analysis from the first 3 years of spectroscopically classified supernovae (SNe).

Data Release	Class Name	Data Type	Publication
Third Year Cosmology Release	SN3YR	Photometric	Brout et al. 2019

Third Year Cosmology Release

class sndata.des.SN3YR

The SN3YR class provides access to data from the first public data release of the Dark Energy Survey Supernova Program, DES-SN3YR. It includes griz light curves of 251 supernovae from the first 3 years of the Dark Energy Survey Supernova Program’s (DES-SN) spectroscopically classified sample. (Source: Brout et al. 2019)

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

Equation of State: Supernovae trace Cosmic Expansion (ESSENCE)

The essence module provides access to data from the Equation of State: Supernovae trace Cosmic Expansion survey (ESSENCE). It includes spectroscopic and photometric data published in Foley et al. 2009 and Narayan et al. 2016 respectively.

Data Release	Class Name	Data Type	Publication
Narayan et al. 2016	Narayan16	photometric	Narayan et al. 2016

Narayan et al. 2016

class sndata.essence.Narayan16

The Narayan16 class provides access to photometric data for 213 Type Ia supernovae discovered by the ESSENCE survey at redshifts 0.1 <= z <= 0.81 between 2002 and 2008. It includes R and I band photometry measured from images obtained using the MOSAIC II camera at the CTIO Blanco telescope. (Source: Narayan et al. 2016)

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

Joint Light-Curve Analysis (JLA)

The jla module provides access to supernova data compiled by the Joint Light-Curve Analysis project. It includes recalibrated light-curves of type Ia supernova (SN Ia) from the SDSS-II and SNLS collaborations.

Data Release	Class name	Data Type	Publication
Betoule et al. 2014	Betoule14	Photometric	Betoule et al. 2014

Betoule et al. 2014

class sndata.jla.Betoule14

The Betoule14 module provides access to light-curves used in a joint analysis of type Ia supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The data set includes several low-redshift samples (z<0.1), all 3 seasons from the SDSS-II (0.05 < z < 0.4), and 3 years from SNLS (0.2 <z < 1) and totals 740 spectroscopically confirmed type Ia supernovae with high quality light curves. (Source: Betoule et al. 2014)

This data set includes observations taken in the pre 2015 MegaCam filter set used by the Canada-France-Hawaii Telescope (CFHT). These filters were measured at multiple positions by both the observing team and manufacturer. Transmission functions registered by this module represent the average transmission across the filter as reported by the manufacturer.

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

Lick Observatory Supernova Search (LOSS)

The loss module provides access to supernova data from the Lick Observatory Supernova Search (LOSS). For the spectroscopic compliment to this survey, see the bsnip module.

Data Release	Class Name	Data Type	Publication
Ganeshalingam et al. 2013	Ganeshalingam13	Photometric	Ganeshalingam et al. 2013

Ganeshalingam et al. 2013

class sndata.loss.Ganeshalingam13

The Ganeshalingam13 class provides access to BVRI light curves of 165 objects published by the first data release of the Lick Observatory Supernova Search (LOSS) conducted between 1998 and 2008. (Source: Ganeshalingam et al. 2013)

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

Sloan Digital Sky Survey (SDSS)

The sdss module provides access to supernova data from the Sloan Digital Sky Survey (SDSS). Please note that access to the photometric and spectroscopic components of the Sako et al. 2018 data release is provided by separate modules.

Data Release	Class name	Data Type	Publication
Sako et al. 2018	Sako18	Photometric	Sako et al. 2018
Sako et al. 2018	Sako18Spec	Spectroscopic	Sako et al. 2018

Sako et al. 2018 (Photometric)

class sndata.sdss.Sako18

The Sako18 class provides access to the photometric data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg2 area along the celestial equator. This data release is comprised of all transient sources brighter than r ≃ 22.5 mag with no history of variability prior to 2004. (Source: Sako et al. 2018)

For the spectroscopic data of this data release see the sako18spec module.

Deviations from the standard UI:

• The get_outliers method returns a dictionary of observations visually flagged by the SDSS team as outliers.

Cuts on returned data:

• Data points manually marked as outliers by the SDSS research time are not included in returned data tables.

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

get_outliers() → dict

Return a dictionary of data points marked by SDSS II as outliers

Returns:[<MJD of bad data point>, …], …} Return type:A dictionary {<obj_id>

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

Sako et al. 2018 (Spectroscopic)

class sndata.sdss.Sako18Spec

The Sako18Spec class provides access to the spectroscopic data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg2 area along the celestial equator. This data release is comprised of all transient sources brighter than r ≃ 22.5 mag with no history of variability prior to 2004. (Source: Sako et al. 2018)

For the photometric data of this data release see the sako18 module.

Deviations from the standard UI:

• None

Cuts on returned data:

• A spectrum is included in the data release for object 15301, but no information about this spectra is provided in the spectra summary table (Table 9). This spectrum is ignored.
• Seven spectroscopically observed objects are missing a reported Ra, Dec, and redshift. These include: 13046, 13346, 15833, 17134, 17135, 19819, and 6471.

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

Supernova Legacy Survey (SNLS)

The snls module provides access to data from the Supernova Legacy Survey. It includes data from the data release of Balland et al. 2009.

Data Release	Class name	Data Type	Publication
Balland et al. 2009	Balland09	Spectroscopic	Balland et al. 2009

Balland et al. 2009

class sndata.snls.Balland09

The Balland09 class provides access to to the three year data release of the Supernova Legacy Survey (SNLS) performed by the Canada-France-Hawaii Telescope (CFHT). It includes 139 spectra of 124 Type Ia supernovae that range from z = 0.149 to z = 1.031 and have an average redshift of z = 0.63 +/- 0.02. (Source: Balland et al. 2009)

Deviations from the standard UI:

• Time values returned in units of phase and not observed Julian date.

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

Sweetspot

The sweetspot module provides access to data from the Sweetspot survey

Data Release	Class Name	Data Type	Publication
Data Release 1	DR1	Photometric	Weyant et al. 2018

Data Release 1

class sndata.sweetspot.DR1

SweetSpot is a 3 yr National Optical Astronomy Observatory (NOAO) survey program to observe Type Ia supernovae (SNe Ia) in the smooth Hubble flow. DR1 includes data from the first half of this survey, including SNe Ia observed in the rest-frame near-infrared (NIR) in the range 0.02 < z < 0.09. Because many observed supernovae require host-galaxy subtraction from templates taken in later semesters, this release contains only the 186 NIR (JHK s ) data points for the 33 SNe Ia that do not require host-galaxy subtraction. (Source: Weyant et al. 2018)

Deviations from the standard UI:

• None

Cuts on returned data:

• None

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

sndata

The sndata package provides access to supernova light-curve data from various surveys while maintaining a consistent data access interface. Each available survey is represented by a dedicated submodule. Each available data release is represented by a dedicated class.

Submodules

base_classes	The base_classes module defines parent classes used by the data access API to define basic data handling and to enforce a consistent user interface.
exceptions	This module defines custom exceptions.
utils	The utils module provides an assorted collection of general utilities used when building data access classes for a given survey / data release.
csp	The csp module provides access to data from the Carnegie Supernova Project (CSP).
des	The des module provides access to data from the Dark Energy Survey (DES).
essence	The essence module provides access to data from the Equation of State: Supernovae trace Cosmic Expansion survey (ESSENCE).
jla	The jla module provides access to supernova data compiled by the Joint Light-Curve Analysis project.
loss	The loss module provides access to supernova data from the Lick Observatory Supernova Search (LOSS).
sdss	The sdss module provides access to supernova data from the Sloan Digital Sky Survey (SDSS).
snls	The snls module provides access to data from the Supernova Legacy Survey.
sweetspot	The sweetspot module provides access to data from the Sweetspot survey

Top Level Functions

sndata.get_zp(band_name: str) → float

Return the zero point used by sndata for a given bandpass

bandpass names are case sensitive.

Parameters:band_name – The name of the sndata bandpass Returns:The zero point as a float

sndata.delete_all_data()

Delete all data downloaded by SNData for all surveys / data releases

sndata.base_classes

The base_classes module defines parent classes used by the data access API to define basic data handling and to enforce a consistent user interface. For an example on how to use these classes to create custom data access module for a new survey / data release, see the Creating Custom Data Classes section of the docs.

Base

class sndata.base_classes.Base

Abstract class acting as a base for all data access classes

_download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

_get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

_get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

_get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

_load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

SpectroscopicRelease

class sndata.base_classes.SpectroscopicRelease(survey_abbrev: str = None, release: str = None)

Generic representation of a spectroscopic data release

This class is a template designed to enforce a consistent user interface and requires child classes to fill in incomplete functionality.

delete_module_data() → None

Delete any data for the current survey / data release

download_module_data(force: bool = False, timeout: float = 15)

Download data for the current survey / data release

Parameters:

• force – Re-Download locally available data
• timeout – Seconds before timeout for individual files/archives

get_available_ids() → List[str]

Return a list of target object IDs for the current survey

Returns:A list of object IDs as strings

get_available_tables() → List[Union[str, int]]

Get Ids for available vizier tables published by this data release

get_data_for_id(obj_id: str, format_table: bool = True) → astropy.table.table.Table

Returns data for a given object ID

See get_available_ids() for a list of available ID values.

Parameters:

• obj_id – The ID of the desired object
• format_table – Format data into the sndata standard format

Returns:

An astropy table of data for the given ID

iter_data(verbose: bool = False, format_table: bool = True, filter_func: bool = None) → astropy.table.table.Table

Iterate through all available targets and yield data tables

An optional progress bar can be formatted by passing a dictionary of tqdm arguments. Outputs can be optionally filtered by passing a function filter_func that accepts a data table and returns a boolean.

Parameters:

• verbose – Optionally display progress bar while iterating
• format_table – Format data for SNCosmo (Default: True)
• filter_func – An optional function to filter outputs by

Yields:

Astropy tables

load_table(table_id: Union[int, str]) → astropy.table.table.Table

Return a Vizier table published by this data release

Parameters:table_id – The published table number or table name

PhotometricRelease

class sndata.base_classes.PhotometricRelease(survey_abbrev: str = None, release: str = None)

Generic representation of a photometric data release

This class is a template designed to enforce a consistent user interface and requires child classes to fill in incomplete functionality.

classmethod get_zp_for_band(band: str) → str

Get the zeropoint for a given band name

Parameters:band – The name of the bandpass

register_filters(force: bool = False)

Register filters for this survey / data release with SNCosmo

Parameters:force – Re-register a band if already registered

DefaultParser

class sndata.base_classes.DefaultParser

Prebuilt data parsing tools for Vizier tables and photometric filters

For more information see the Creating Custom Data Classes section of the docs.

_get_available_tables() → List[Union[str, int]]

Default backend functionality of get_available_tables function

_load_table(table_id: Union[int, str]) → astropy.table.table.Table

Default backend functionality of load_table function

_register_filters(force: bool = False)

Default backend functionality of register_filters function

sndata.utils

The utils module provides an assorted collection of general utilities used when building data access classes for a given survey / data release.

sndata.utils.data_parsing

The data_parsing module provides file parsing tools for any file formats used by multiple astronomical surveys and / or data releases. It is also responsible for locating and registering data located on the local machine.

sndata.utils.data_parsing.find_data_dir(survey_abbrev: str, release: str) → pathlib.Path

Determine the directory where data files are stored for a data release

If the directory does not exist, create it.

Parameters:

• survey_abbrev – Abbreviation of the survey to load data for (e.g., CSP)
• release – Name of the data release from the survey (e.g., DR1)

Returns:

The path of the directory where

sndata.utils.data_parsing.parse_vizier_table_descriptions(readme_path: Union[pathlib.Path, str])

Returns the table descriptions from a vizier readme file

Parameters:readme_path – Path of the file to read Returns:<Table description (str)>} Return type:A dictionary {<Table number (int)>

sndata.utils.data_parsing.register_filter_file(file_path: str, filter_name: str, force: bool = False)

Registers filter profiles with sncosmo if not already registered

Assumes the file at file_path is a two column, white space delimited ascii table.

Parameters:

• file_path – Path of ascii table with wavelength (Ang) and transmission
• filter_name – The name of the registered filter.
• force – Whether to re-register a band if already registered

sndata.utils.data_parsing.require_data_path(*data_dirs)

Raise NoDownloadedData exception if given paths don’t exist

Parameters:*data_dirs – Path objects to check exists

sndata.utils.downloads

The downloads module supports downloading data files in various file formats.

sndata.utils.downloads.download_file(url: str, destination: Union[str, pathlib.Path, IO] = None, force: bool = False, timeout: float = 15, verbose: bool = True)

Download content from a url to a file

If destination is a path but already exists, skip the download unless force is also True.

Parameters:

• url – URL of the file to download
• destination – Path or file object to download to
• force – Re-Download locally available data (Default: False)
• timeout – Seconds before raising timeout error (Default: 15)
• verbose – Print status to stdout

sndata.utils.downloads.download_tar(url: str, out_dir: str, mode: str = 'r:gz', force: bool = False, timeout: float = 15, skip_exists: str = None)

Download and unzip a .tar.gz file to a given output directory

Parameters:

• url – URL of the file to download
• out_dir – The directory to unzip file contents to
• mode – Compression mode (Default: r:gz)
• force – Re-Download locally available data (Default: False)
• timeout – Seconds before raising timeout error (Default: 15)
• skip_exists – Optionally skip the download if given path exists

sndata.utils.unit_conversion

The unit_conversion handles the conversion of values between different units / timezones / systems of measurement.

sndata.utils.unit_conversion.hourangle_to_degrees(rah: float, ram: float, ras: float, dec_sign: str, decd: float, decm: float, decs: float) -> (<class 'float'>, <class 'float'>)

Convert from hour angle to degrees

Parameters:

• rah – RA hours
• ram – RA arcminutes
• ras – RA arcseconds
• dec_sign – Sign of the declination (‘+’ or ‘-‘)
• decd – Dec degrees
• decm – Dec arcmin
• decs – Dec arcsec

sndata.utils.wrappers

The wrappers contains function or object wrappers used by the parent package.

sndata.utils.wrappers.build_pbar(data: iter, verbose: Union[bool, dict])

Cast an iterable into a progress bar

If verbose is False, return data unchanged.

Parameters:

• data – An iterable object
• verbose – Arguments for tqdm.tqdm

sndata.utils.wrappers.ignore_warnings_wrapper(func: callable) → callable

Ignores warnings issued by the wrapped function call

sndata.utils.wrappers.lru_copy_cache(maxsize: int = 128, typed: bool = False, copy: bool = True)

Decorator to cache the return of a function

Similar to functools.lru_cache, but allows a copy of the cached value to be returned, thus preventing mutation of the cache.

Parameters:

• maxsize – Maximum size of the cache
• typed – Cache objects of different types separately (Default: False)
• copy – Return a copy of the cached item (Default: True)

Returns:

A decorator