ExternalArrayReference¶
-
class
asdf.
ExternalArrayReference
(fileuri, target, dtype, shape)[source]¶ Bases:
asdf.types.AsdfType
Store a reference to an array in an external File.
This class is a simple way of referring to an array in another file. It provides no way to resolve these references, that is left to the user. It also performs no checking to see if any of the arguments are correct. e.g. if the file exits.
- Parameters
- fileuri: `str`
The path to the path to be referenced. Can be relative to the file containing the reference.
- target: `object`
Some internal target to the data in the file. Examples may include a HDU index, a HDF path or an asdf fragment.
- dtype: `str`
The (numpy) dtype of the contained array.
- shape: `tuple`
The shape of the array to be loaded.
Examples
>>> import asdf >>> ref = asdf.ExternalArrayReference("myfitsfile.fits", 1, "float64", (100, 100)) >>> tree = {'reference': ref} >>> with asdf.AsdfFile(tree) as ff: ... ff.write_to("test.asdf")
Attributes Summary
Methods Summary
from_tree
(tree, ctx)Converts basic types representing YAML trees into custom types.
from_tree_tagged
(tree, ctx)Converts from tagged tree into custom type.
incompatible_version
(version)Indicates if given version is known to be incompatible with this type.
make_yaml_tag
(name[, versioned])Given the name of a type, returns a string representing its YAML tag.
names
()Returns the name(s) represented by this tag type as a list.
subclass
(*args[, attribute])Decorator to enable serialization of a subclass of an existing type.
subclass_property
(attribute)Decorator to enable serialization of custom subclass attributes.
tag_base
()Returns the base of the YAML tag for types represented by this class.
to_tree
(data, ctx)Converts instances of custom types into YAML representations.
to_tree_tagged
(node, ctx)Converts instances of custom types into tagged objects.
Attributes Documentation
-
handle_dynamic_subclasses
= False¶
-
has_required_modules
= True¶
-
name
= 'core/externalarray'¶
-
organization
= 'stsci.edu'¶
-
requires
= []¶
-
standard
= 'asdf'¶
-
supported_versions
= []¶
-
types
= []¶
-
validators
= {}¶
-
version
= AsdfVersion('1.0.0')¶
-
yaml_tag
= 'tag:stsci.edu:asdf/core/externalarray-1.0.0'¶
Methods Documentation
-
classmethod
from_tree
(tree, ctx)[source]¶ Converts basic types representing YAML trees into custom types.
This method should be overridden by custom extension classes in order to define how custom types are deserialized from the YAML representation back into their original types. Typically the method will return an instance of the original custom type. It is also permitted to return a generator, which yields a partially constructed result, then completes construction once the generator is drained. This is useful when constructing objects that contain reference cycles.
This method is called as part of the process of reading an ASDF file in order to construct an
AsdfFile
object. Whenever a YAML subtree is encountered that has a tag that corresponds to theyaml_tag
property of this class, this method will be used to deserialize that tree back into an instance of the original custom type.- Parameters
- Returns
- An instance of the custom type represented by this extension class,
or a generator that yields that instance.
-
classmethod
from_tree_tagged
(tree, ctx)¶ Converts from tagged tree into custom type.
It is more common for extension classes to override
from_tree
instead of this method. This method should only be overridden if it is necessary to access the_tag
property of theTagged
object directly.
-
classmethod
incompatible_version
(version)¶ Indicates if given version is known to be incompatible with this type.
If this tag class explicitly identifies compatible versions then this checks whether a given version is compatible or not (see
supported_versions
). Otherwise, all versions are assumed to be compatible.Child classes can override this method to affect how version compatiblity for this type is determined.
- Parameters
- version
str
orAsdfVersion
The version to test for compatibility.
- version
-
classmethod
make_yaml_tag
(name, versioned=True)¶ Given the name of a type, returns a string representing its YAML tag.
- Parameters
- namestr
The name of the type. In most cases this will correspond to the
name
attribute of the tag type. However, it is passed as a parameter since some tag types represent multiple custom types.- versionedbool
If
True
, the tag will be versioned. Otherwise, a YAML tag without a version will be returned.
- Returns
str
representing the YAML tag
-
classmethod
names
()¶ Returns the name(s) represented by this tag type as a list.
While some tag types represent only a single custom type, others represent multiple types. In the latter case, the
name
attribute of the extension is actually a list, not simply a string. This method normalizes the value ofname
by returning a list in all cases.- Returns
list
of names represented by this tag type
-
classmethod
subclass
(*args, attribute='subclass')¶ Decorator to enable serialization of a subclass of an existing type.
Use this method to decorate subclasses of custom types that are already handled by an existing ASDF tag class. This enables subclasses of known types to be properly serialized without having to write an entirely separate tag class for the subclass.
This feature can only be used for tagged types where the underlying YAML representation of the type is an object (i.e. a Python
dict
). It will not work for nodes that are basic types.The subclass metadata is stored in a new attribute of the YAML node. By default the attribute name is “subclass”, but it is customizable by using the optional
attribute
keyword argument of the decorator.The schema of the base custom type is used for validation. This feature will not work if the base schema disallows additional attributes.
It is incumbent upon the user to avoid name conflicts with attributes that already exist in the representation of the base custom class. For example, a base class may use the attribute “subclass” for some other purpose, in which case it would be necessary to provide a different custom attribute name here.
- Parameters
- attribute
str
Custom attribute name used to store subclass metadata in this node.
- attribute
-
classmethod
subclass_property
(attribute)¶ Decorator to enable serialization of custom subclass attributes.
Use this decorator to serialize attributes that are specific to a subclass of a custom type that is already handled by an existing ASDF tag class. This decorator will only work on subclasses that have been decorated with the
subclass
decorator.Methods that are decorated in this way are treated as properties (see
property
). The name of the property must correspond to a keyword argument of the subclass constructor.The property will be serialized as a YAML object attribute with the same name. Users are responsible for ensuring that any and all additional subclass properties conform to the schema of the base custom type and do not conflict with existing attributes.
-
classmethod
tag_base
()¶ Returns the base of the YAML tag for types represented by this class.
This method returns the portion of the tag that represents the standard and the organization of any type represented by this class.
- Returns
str
representing the base of the YAML tag
-
classmethod
to_tree
(data, ctx)[source]¶ Converts instances of custom types into YAML representations.
This method should be overridden by custom extension classes in order to define how custom types are serialized into YAML. The method must return a single Python object corresponding to one of the basic YAML types (dict, list, str, or number). However, the types can be nested and combined in order to represent more complex custom types.
This method is called as part of the process of writing an
AsdfFile
object. Whenever a custom type (or a subclass of that type) that is listed in thetypes
attribute of this class is encountered, this method will be used to serialize that type.The name
to_tree
refers to the act of converting a custom type into part of a YAML object tree.- Parameters
- Returns