FitsImageFormatterBase

class lsst.obs.base.formatters.fitsExposure.FitsImageFormatterBase(file_descriptor: FileDescriptor, *, ref: DatasetRef, write_parameters: Mapping[str, Any] | None = None, write_recipes: Mapping[str, Any] | None = None, **kwargs: Any)

Bases: FormatterV2

Base class formatter for image-like storage classes stored via FITS.

Notes

This class makes no assumptions about how many HDUs are used to represent the image on disk, and includes no support for writing. It’s really just a collection of miscellaneous boilerplate common to all FITS image formatters.

Concrete subclasses must implement readComponent, readFull, and write_local_file (even if just to disable them by raising an exception).

Attributes Summary

can_read_from_local_file	Declare whether read_from_local_file is available to this formatter.
checked_parameters	The parameters passed by the butler user, after checking them against the storage class and transforming None into an empty dict (dict).
default_extension	Default extension to use when writing a file.
reader	The reader object that backs this formatter's read operations.
storageClass_dtype	The numpy data type associated with the storage class.
supported_extensions	Set of all extensions supported by this formatter.
unsupported_parameters	Support all parameters.

Methods Summary

readComponent(component)	Read a component dataset.
readFull()	Read the full dataset (while still accounting for parameters).
read_from_local_file(path[, component, ...])	Read a dataset from a URI guaranteed to refer to the local file system.

Attributes Documentation

can_read_from_local_file: ClassVar[bool] = True

Declare whether read_from_local_file is available to this formatter.

checked_parameters

The parameters passed by the butler user, after checking them against the storage class and transforming None into an empty dict (dict).

This is computed on first use and then cached. It should never be accessed when writing. Subclasses that need additional checking should delegate to super and then check the result before returning it.

default_extension: ClassVar[str | None] = '.fits'

Default extension to use when writing a file.

Can be None if the extension is determined dynamically. Use the get_write_extension method to get the actual extension to use.

reader

The reader object that backs this formatter’s read operations.

This is computed on first use and then cached. It should never be accessed when writing. Currently assumes a local file.

storageClass_dtype

The numpy data type associated with the storage class.

supported_extensions: ClassVar[Set[str]] = frozenset({'.fit', '.fits', '.fits.fz', '.fits.gz', '.fz'})

Set of all extensions supported by this formatter.

Any extension assigned to the default_extension property will be automatically included in the list of supported extensions.

unsupported_parameters: ClassVar[Set[str]] = frozenset({})

Support all parameters.

Methods Documentation

abstract readComponent(component: str) → Any

Read a component dataset.

Parameters

componentstr, optional

Component to read from the file.

Returns

objtyping.Any

In-memory component object.

Raises

KeyError

Raised if the requested component cannot be handled.

abstract readFull() → Any

Read the full dataset (while still accounting for parameters).

Returns

objtyping.Any

In-memory component object.

read_from_local_file(path: str, component: str | None = None, expected_size: int = -1) → Any

Read a dataset from a URI guaranteed to refer to the local file system.

Parameters

pathstr

Path to a local file that should be read.

componentstr or None, optional

The component to be read from the dataset.

expected_sizeint, optional

If known, the expected size of the resource to read. This can be -1 indicates the file size is not known.

Returns

in_memory_datasetobject or NotImplemented

The Python object read from the resource or NotImplemented.

Raises

lsst.daf.butler.FormatterNotImplementedError

Raised if there is no implementation written to read data from a local file.

Notes

This method will only be called if the class property can_read_from_local_file is True and other options were not used.