altair.LayerSpec

class altair.LayerSpec(layer=Undefined, data=Undefined, description=Undefined, encoding=Undefined, height=Undefined, name=Undefined, projection=Undefined, resolve=Undefined, title=Undefined, transform=Undefined, view=Undefined, width=Undefined, **kwds)

LayerSpec schema wrapper

Mapping(required=[layer]) A full layered plot specification, which may contains encoding and projection properties that will be applied to underlying unit (single-view) specifications.

Attributes

layerList(anyOf(LayerSpec, UnitSpec))

Layer or single view specifications to be layered.

Note : Specifications inside layer cannot use row and column channels as layering facet specifications is not allowed. Instead, use the facet operator and place a layer inside a facet.

dataanyOf(Data, None)

An object describing the data source. Set to null to ignore the parent’s data source. If no data is set, it is derived from the parent.

descriptionstring

Description of this mark for commenting purpose.

encodingEncoding

A shared key-value mapping between encoding channels and definition of fields in the underlying layers.

heightanyOf(float, enum(‘container’), Step)

The height of a visualization.

• For a plot with a continuous y-field, height should be a number.

• For a plot with either a discrete y-field or no y-field, height can be either a number indicating a fixed height or an object in the form of {step: number} defining the height per discrete step. (No y-field is equivalent to having one discrete step.)

• To enable responsive sizing on height, it should be set to "container".

Default value: Based on config.view.continuousHeight for a plot with a continuous y-field and config.view.discreteHeight otherwise.

Note: For plots with row and column channels, this represents the height of a single view and the "container" option cannot be used.

See also: height documentation.

namestring

Name of the visualization for later reference.

projectionProjection

An object defining properties of the geographic projection shared by underlying layers.

resolveResolve

Scale, axis, and legend resolutions for view composition specifications.

titleanyOf(Text, TitleParams)

Title for the plot.

transformList(Transform)

An array of data transformations such as filter and new field calculation.

viewViewBackground

An object defining the view background’s fill and stroke.

Default value: none (transparent)

widthanyOf(float, enum(‘container’), Step)

The width of a visualization.

• For a plot with a continuous x-field, width should be a number.

• For a plot with either a discrete x-field or no x-field, width can be either a number indicating a fixed width or an object in the form of {step: number} defining the width per discrete step. (No x-field is equivalent to having one discrete step.)

• To enable responsive sizing on width, it should be set to "container".

Default value: Based on config.view.continuousWidth for a plot with a continuous x-field and config.view.discreteWidth otherwise.

Note: For plots with row and column channels, this represents the width of a single view and the "container" option cannot be used.

See also: width documentation.

__init__(self, layer=Undefined, data=Undefined, description=Undefined, encoding=Undefined, height=Undefined, name=Undefined, projection=Undefined, resolve=Undefined, title=Undefined, transform=Undefined, view=Undefined, width=Undefined, **kwds)

Initialize self. See help(type(self)) for accurate signature.

Methods

__init__(self[, layer, data, description, …])	Initialize self.
copy(self[, deep, ignore])	Return a copy of the object
from_dict(dct[, validate, _wrapper_classes])	Construct class from a dictionary representation
from_json(json_string[, validate])	Instantiate the object from a valid JSON string
resolve_references([schema])	Resolve references in the context of this object’s schema or root schema.
to_dict(self[, validate, ignore, context])	Return a dictionary representation of the object
to_json(self[, validate, ignore, context, …])	Emit the JSON representation for this object as a string.
validate(instance[, schema])	Validate the instance against the class schema in the context of the rootschema.
validate_property(name, value[, schema])	Validate a property against property schema in the context of the rootschema

copy(self, deep=True, ignore=())

Return a copy of the object

Parameters

deepboolean or list, optional

If True (default) then return a deep copy of all dict, list, and SchemaBase objects within the object structure. If False, then only copy the top object. If a list or iterable, then only copy the listed attributes.

ignorelist, optional

A list of keys for which the contents should not be copied, but only stored by reference.

classmethod from_dict(dct, validate=True, _wrapper_classes=None)

Construct class from a dictionary representation

Parameters

dctdictionary

The dict from which to construct the class

validateboolean

If True (default), then validate the input against the schema.

_wrapper_classeslist (optional)

The set of SchemaBase classes to use when constructing wrappers of the dict inputs. If not specified, the result of cls._default_wrapper_classes will be used.

Returns

objSchema object

The wrapped schema

Raises

jsonschema.ValidationError :

if validate=True and dct does not conform to the schema

classmethod from_json(json_string, validate=True, **kwargs)

Instantiate the object from a valid JSON string

Parameters

json_stringstring

The string containing a valid JSON chart specification.

validateboolean

If True (default), then validate the input against the schema.

**kwargs :

Additional keyword arguments are passed to json.loads

Returns

chartChart object

The altair Chart object built from the specification.

classmethod resolve_references(schema=None)

Resolve references in the context of this object’s schema or root schema.

to_dict(self, validate=True, ignore=None, context=None)

Return a dictionary representation of the object

Parameters

validateboolean or string

If True (default), then validate the output dictionary against the schema. If “deep” then recursively validate all objects in the spec. This takes much more time, but it results in friendlier tracebacks for large objects.

ignorelist

A list of keys to ignore. This will not passed to child to_dict function calls.

contextdict (optional)

A context dictionary that will be passed to all child to_dict function calls

Returns

dctdictionary

The dictionary representation of this object

Raises

jsonschema.ValidationError :

if validate=True and the dict does not conform to the schema

to_json(self, validate=True, ignore=[], context={}, indent=2, sort_keys=True, **kwargs)

Emit the JSON representation for this object as a string.

Parameters

validateboolean or string

If True (default), then validate the output dictionary against the schema. If “deep” then recursively validate all objects in the spec. This takes much more time, but it results in friendlier tracebacks for large objects.

ignorelist

A list of keys to ignore. This will not passed to child to_dict function calls.

contextdict (optional)

A context dictionary that will be passed to all child to_dict function calls

indentinteger, default 2

the number of spaces of indentation to use

sort_keysboolean, default True

if True, sort keys in the output

**kwargs

Additional keyword arguments are passed to json.dumps()

Returns

specstring

The JSON specification of the chart object.

classmethod validate(instance, schema=None)

Validate the instance against the class schema in the context of the rootschema.

classmethod validate_property(name, value, schema=None)

Validate a property against property schema in the context of the rootschema