altair.DensityTransform

class altair.DensityTransform(density=Undefined, bandwidth=Undefined, counts=Undefined, cumulative=Undefined, extent=Undefined, groupby=Undefined, maxsteps=Undefined, minsteps=Undefined, steps=Undefined, **kwds)

DensityTransform schema wrapper

Mapping(required=[density])

Attributes

densityFieldName

The data field for which to perform density estimation.

bandwidthfloat

The bandwidth (standard deviation) of the Gaussian kernel. If unspecified or set to zero, the bandwidth value is automatically estimated from the input data using Scott’s rule.

countsboolean

A boolean flag indicating if the output values should be probability estimates (false) or smoothed counts (true).

Default value: false

cumulativeboolean

A boolean flag indicating whether to produce density estimates (false) or cumulative density estimates (true).

Default value: false

extentList([float, float])

A [min, max] domain from which to sample the distribution. If unspecified, the extent will be determined by the observed minimum and maximum values of the density value field.

groupbyList(FieldName)

The data fields to group by. If not specified, a single group containing all data objects will be used.

maxstepsfloat

The maximum number of samples to take along the extent domain for plotting the density.

Default value: 200

minstepsfloat

The minimum number of samples to take along the extent domain for plotting the density.

Default value: 25

stepsfloat

The exact number of samples to take along the extent domain for plotting the density. If specified, overrides both minsteps and maxsteps to set an exact number of uniform samples. Potentially useful in conjunction with a fixed extent to ensure consistent sample points for stacked densities.

asList([FieldName, FieldName])

The output fields for the sample value and corresponding density estimate.

Default value: ["value", "density"]

__init__(self, density=Undefined, bandwidth=Undefined, counts=Undefined, cumulative=Undefined, extent=Undefined, groupby=Undefined, maxsteps=Undefined, minsteps=Undefined, steps=Undefined, **kwds)

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

Methods

__init__(self[, density, bandwidth, counts, …])	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