FitsImageFormatter¶

class lsst.obs.base.formatters.fitsExposure.FitsImageFormatter(fileDescriptor: FileDescriptor, dataId: DataCoordinate, writeParameters: Optional[Dict[str, Any]] = None, writeRecipes: Optional[Dict[str, Any]] = None)¶

Bases: lsst.obs.base.formatters.fitsExposure.FitsImageFormatterBase

Specialisation for Image reading.

Attributes Summary

`dataId`	Return Data ID associated with this formatter (`DataCoordinate`).
`extension`
`fileDescriptor`	File descriptor associated with this formatter (`FileDescriptor`).
`metadata`	The metadata read from this file.
`supportedExtensions`	Set of all extensions supported by this formatter.
`supportedWriteParameters`	Parameters understood by this formatter that can be used to control how a dataset is serialized.
`unsupportedParameters`	Support all parameters.
`writeParameters`	Parameters to use when writing out datasets.
`writeRecipes`	Detailed write Recipes indexed by recipe name.

Methods Summary

`can_read_bytes`()	Indicate if this formatter can format from bytes.
`fromBytes`(serializedDataset[, component])	Read serialized data into a Dataset or its component.
`getImageCompressionSettings`(recipeName)	Retrieve the relevant compression settings for this recipe.
`makeUpdatedLocation`(location)	Return a new `Location` updated with this formatter’s extension.
`name`()	Return the fully qualified name of the formatter.
`predictPath`()	Return the path that would be returned by write.
`read`([component])	Read data from a file.
`readComponent`(component[, parameters])	Read a component held by the Exposure.
`readFull`([parameters])	Read the full Exposure object.
`readMetadata`()	Read all header metadata directly into a PropertyList.
`segregateParameters`([parameters])	Segregate the supplied parameters.
`stripMetadata`()	Remove metadata entries that are parsed into components.
`toBytes`(inMemoryDataset)	Serialize the Dataset to bytes based on formatter.
`validateExtension`(location)	Check the extension of the provided location for compatibility.
`validateWriteRecipes`(recipes)	Validate supplied recipes for this formatter.
`write`(inMemoryDataset)	Write a Python object to a file.

Attributes Documentation

dataId¶: Return Data ID associated with this formatter (DataCoordinate).

extension = '.fits'¶

fileDescriptor¶

File descriptor associated with this formatter (FileDescriptor).

Read-only property.

metadata¶: The metadata read from this file. It will be stripped as components are extracted from it (lsst.daf.base.PropertyList).

supportedExtensions: ClassVar[AbstractSet[str]] = frozenset({'.fit', '.fits', '.fits.fz', '.fits.gz', '.fz'})¶

Set of all extensions supported by this formatter.

Only expected to be populated by Formatters that write files. Any extension assigned to the extension property will be automatically included in the list of supported extensions.

supportedWriteParameters: ClassVar[Optional[AbstractSet[str]]] = frozenset({'recipe'})¶: Parameters understood by this formatter that can be used to control how a dataset is serialized. None indicates that no parameters are supported.

unsupportedParameters: ClassVar[Optional[AbstractSet[str]]] = {}¶: Support all parameters.

writeParameters¶: Parameters to use when writing out datasets.

writeRecipes¶: Detailed write Recipes indexed by recipe name.

Methods Documentation

classmethod can_read_bytes() → bool ¶

Indicate if this formatter can format from bytes.

Returns

canbool: True if the fromBytes method is implemented.

fromBytes(serializedDataset: bytes, component: Optional[str] = None) → object ¶

Read serialized data into a Dataset or its component.

Parameters

serializedDatasetbytes: Bytes object to unserialize.
componentstr, optional: Component to read from the Dataset. Only used if the StorageClass for reading differed from the StorageClass used to write the file.

Returns

inMemoryDatasetobject: The requested data as a Python object. The type of object is controlled by the specific formatter.

getImageCompressionSettings(recipeName)¶

Retrieve the relevant compression settings for this recipe.

Parameters

recipeNamestr: Label associated with the collection of compression parameters to select.

Returns

settingsdict: The selected settings.

makeUpdatedLocation(location: lsst.daf.butler.Location) → lsst.daf.butler.Location¶

Return a new Location updated with this formatter’s extension.

Parameters

locationLocation: The location to update.

Returns

updatedLocation: A new Location with a new file extension applied.

Raises

NotImplementedError: Raised if there is no extension attribute associated with this formatter.

Notes

This method is available to all Formatters but might not be implemented by all formatters. It requires that a formatter set an extension attribute containing the file extension used when writing files. If extension is None the supplied file will not be updated. Not all formatters write files so this is not defined in the base class.

classmethod name() → str ¶

Return the fully qualified name of the formatter.

Returns

namestr: Fully-qualified name of formatter class.

predictPath() → str ¶

Return the path that would be returned by write.

Does not write any data file.

Uses the FileDescriptor associated with the instance.

Returns

pathstr: Path within datastore that would be associated with the location stored in this Formatter.

read(component=None)¶

Read data from a file.

Parameters

componentstr, optional: Component to read from the file. Only used if the StorageClass for reading differed from the StorageClass used to write the file.

Returns

inMemoryDatasetobject: The requested data as a Python object. The type of object is controlled by the specific formatter.

Raises

ValueError: Component requested but this file does not seem to be a concrete composite.
KeyError: Raised when parameters passed with fileDescriptor are not supported.

readComponent(component, parameters=None)¶

Read a component held by the Exposure.

Parameters

componentstr, optional: Component to read from the file.
parametersdict, optional: If specified, a dictionary of slicing parameters that overrides those in fileDescriptor.

Returns

objcomponent-dependent: In-memory component object.

Raises

KeyError: Raised if the requested component cannot be handled.

readFull(parameters=None)¶

Read the full Exposure object.

Parameters

parametersdict, optional: If specified a dictionary of slicing parameters that overrides those in fileDescriptor.

Returns

exposureExposure: Complete in-memory exposure.

readMetadata()¶

Read all header metadata directly into a PropertyList.

Returns

metadataPropertyList: Header metadata.

segregateParameters(parameters: Optional[Dict[str, Any]] = None) → Tuple[Dict, Dict]¶

Segregate the supplied parameters.

This splits the parameters into those understood by the formatter and those not understood by the formatter.

Any unsupported parameters are assumed to be usable by associated assemblers.

Parameters

parametersdict, optional: Parameters with values that have been supplied by the caller and which might be relevant for the formatter. If None parameters will be read from the registered FileDescriptor.

Returns

supporteddict: Those parameters supported by this formatter.
unsupporteddict: Those parameters not supported by this formatter.

stripMetadata()¶

Remove metadata entries that are parsed into components.

This is only called when just the metadata is requested; stripping entries there forces code that wants other components to ask for those components directly rather than trying to extract them from the metadata manually, which is fragile. This behavior is an intentional change from Gen2.

Parameters

metadataPropertyList: Header metadata, to be modified in-place.

toBytes(inMemoryDataset: Any) → bytes ¶

Serialize the Dataset to bytes based on formatter.

Parameters

inMemoryDatasetobject: The Python object to serialize.

Returns

serializedDatasetbytes: Bytes representing the serialized dataset.

classmethod validateExtension(location: lsst.daf.butler.Location) → None ¶

Check the extension of the provided location for compatibility.

Parameters

locationLocation: Location from which to extract a file extension.

Raises

NotImplementedError: Raised if file extensions are a concept not understood by this formatter.
ValueError: Raised if the formatter does not understand this extension.

Notes

This method is available to all Formatters but might not be implemented by all formatters. It requires that a formatter set an extension attribute containing the file extension used when writing files. If extension is None only the set of supported extensions will be examined.

classmethod validateWriteRecipes(recipes)¶

Validate supplied recipes for this formatter.

The recipes are supplemented with default values where appropriate.

TODO: replace this custom validation code with Cerberus (DM-11846)

Parameters

recipesdict: Recipes to validate. Can be empty dict or None.

Returns

validateddict: Validated recipes. Returns what was given if there are no recipes listed.

Raises

RuntimeError: Raised if validation fails.

write(inMemoryDataset)¶

Write a Python object to a file.

Parameters

inMemoryDatasetobject: The Python object to store.

Navigation

FitsImageFormatter¶