JwstDataModel

class jwst.datamodels.JwstDataModel(init=None, schema=None, memmap=False, pass_invalid_values=None, strict_validation=None, validate_on_assignment=None, cast_fits_arrays=True, validate_arrays=False, ignore_missing_extensions=True, **kwargs)

Bases: DataModel

Parameters

• init (str, tuple, HDUList, ndarray, dict, None) –

  • None : Create a default data model with no shape.

  • tuple : Shape of the data array. Initialize with empty data array with shape specified by the.

  • file path: Initialize from the given file (FITS or ASDF)

  • readable file object: Initialize from the given file object

  • HDUList : Initialize from the given HDUList.

  • A numpy array: Used to initialize the data array

  • dict: The object model tree for the data model

• schema (dict, str (optional)) – Tree of objects representing a JSON schema, or string naming a schema. The schema to use to understand the elements on the model. If not provided, the schema associated with this class will be used.

• memmap (bool) – Turn memmap of FITS file on or off. (default: False). Ignored for ASDF files.

• pass_invalid_values (bool or None) – If True, values that do not validate the schema will be added to the metadata. If False, they will be set to None. If None, value will be taken from the environmental PASS_INVALID_VALUES. Otherwise the default value is False.

• strict_validation (bool or None) – If True, schema validation errors will generate an exception. If False, they will generate a warning. If None, value will be taken from the environmental STRICT_VALIDATION. Otherwise, the default value is False.

• validate_on_assignment (bool or None) – Defaults to ‘None’. If None, value will be taken from the environmental VALIDATE_ON_ASSIGNMENT, defaulting to ‘True’ if no environment variable is set. If ‘True’, attribute assignments are validated at the time of assignment. Validation errors generate warnings and values will be set to None. If ‘False’, schema validation occurs only once at the time of write. Validation errors generate warnings.

• cast_fits_arrays (bool) – If True, arrays will be cast to the dtype described by the schema when read from a FITS file. If False, arrays will be read without casting.

• validate_arrays (bool) – If True, arrays will be validated against ndim, max_ndim, and datatype validators in the schemas.

• ignore_missing_extensions (bool) – When False, raise warnings when a file is read that contains metadata about extensions that are not available. Defaults to True.

• kwargs (dict) –

  Additional keyword arguments passed to lower level functions. These arguments are generally file format-specific. Arguments of note are:

  • FITS

    skip_fits_update - bool or None

    True to skip updating the ASDF tree from the FITS headers, if possible. If None, value will be taken from the environmental SKIP_FITS_UPDATE. Otherwise, the default value is True.

Attributes Summary

crds_observatory	Get CRDS observatory code for this model.
schema_url	The schema URI to validate the model against.

Methods Summary

get_crds_parameters()	Get parameters used by CRDS to select references for this model.
on_init(init)	Hook invoked by the base class before returning a newly created model instance.
on_save(init)	Hook invoked by the base class before writing a model to a file (FITS or ASDF).

Attributes Documentation

crds_observatory

Get CRDS observatory code for this model.

Return type

str

schema_url = 'http://stsci.edu/schemas/jwst_datamodel/core.schema'

The schema URI to validate the model against. If None, only basic validation of required metadata properties (filename, model_type) will occur.

Methods Documentation

get_crds_parameters()

Get parameters used by CRDS to select references for this model.

Return type

dict

on_init(init)

Hook invoked by the base class before returning a newly created model instance.

on_save(init)

Hook invoked by the base class before writing a model to a file (FITS or ASDF).