Formatter¶

class lsst.daf.butler.Formatter(fileDescriptor: FileDescriptor, dataId: DataCoordinate, writeParameters: Optional[Dict[str, Any]] = None, writeRecipes: Optional[Dict[str, Any]] = None)¶

Bases: object

Interface for reading and writing Datasets.

The formatters are associated with a particular StorageClass.

Parameters:

fileDescriptor : FileDescriptor, optional: Identifies the file to read or write, and the associated storage classes and parameter information. Its value can be None if the caller will never call Formatter.read or Formatter.write.
dataId : DataCoordinate: Data ID associated with this formatter.
writeParameters : dict, optional: Any parameters to be hard-coded into this instance to control how the dataset is serialized.
writeRecipes : dict, optional: Detailed write Recipes indexed by recipe name.

Notes

All Formatter subclasses should share the base class’s constructor signature.

Attributes Summary

`dataId`	Return Data ID associated with this formatter (`DataCoordinate`).
`fileDescriptor`	File descriptor associated with this formatter (`FileDescriptor`).
`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`	Set of read parameters not understood by this `Formatter`.
`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.
`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 a Dataset.
`segregateParameters`(parameters, Any]] = None)	Segregate the supplied parameters.
`toBytes`(inMemoryDataset)	Serialize the Dataset to bytes based on formatter.
`validateExtension`(location)	Check the extension of the provided location for compatibility.
`validateWriteRecipes`(recipes, Any]])	Validate supplied recipes for this formatter.
`write`(inMemoryDataset)	Write a Dataset.

Attributes Documentation

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

fileDescriptor¶

File descriptor associated with this formatter (FileDescriptor).

Read-only property.

supportedExtensions = frozenset()¶

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 = None¶: Parameters understood by this formatter that can be used to control how a dataset is serialized. None indicates that no parameters are supported.

unsupportedParameters = frozenset()¶: Set of read parameters not understood by this Formatter. An empty set means all parameters are supported. None indicates that no parameters are supported. These param (frozenset).

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:	can : `bool` `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:	serializedDataset : `bytes` Bytes object to unserialize. component : `str`, optional Component to read from the Dataset. Only used if the `StorageClass` for reading differed from the `StorageClass` used to write the file.
Returns:	inMemoryDataset : `object` The requested data as a Python object. The type of object is controlled by the specific formatter.

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

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

Parameters:	location : `Location` The location to update.
Returns:	updated : `Location` 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:	name : `str` 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:	path : `str` Path within datastore that would be associated with the location stored in this `Formatter`.

read(component: Optional[str] = None) → Any¶

Read a Dataset.

Parameters:	component : `str`, optional Component to read from the file. Only used if the `StorageClass` for reading differed from the `StorageClass` used to write the file.
Returns:	inMemoryDataset : `object` The requested Dataset.

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

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:	parameters : `dict`, 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:	supported : `dict` Those parameters supported by this formatter. unsupported : `dict` Those parameters not supported by this formatter.

toBytes(inMemoryDataset: Any) → bytes¶

Serialize the Dataset to bytes based on formatter.

Parameters:	inMemoryDataset : `object` The Python object to serialize.
Returns:	serializedDataset : `bytes` Bytes representing the serialized dataset.

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

Check the extension of the provided location for compatibility.

Parameters:	location : `Location` 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: Optional[Mapping[str, Any]]) → Optional[Mapping[str, Any]]¶

Validate supplied recipes for this formatter.

The recipes are supplemented with default values where appropriate.

Parameters:	recipes : `dict` Recipes to validate.
Returns:	validated : `dict` Validated recipes.
Raises:	RuntimeError Raised if validation fails. The default implementation raises if any recipes are given.

write(inMemoryDataset: Any) → None¶

Write a Dataset.

Parameters:	inMemoryDataset : `object` The Dataset to store.

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Formatter¶