# Subexpression class¶

(Shortest import: from brian2.core.variables import Subexpression)

class brian2.core.variables.Subexpression(name, owner, expr, device, dimensions=Dimension(), dtype=None, scalar=False)[source]

An object providing information about a named subexpression in a model. Most of the time Variables.add_subexpression should be used instead of instantiating this class directly.

Parameters

name : str

The name of the subexpression.

dimensions : Dimension, optional

The physical dimensions of the subexpression.

owner : Group

The group to which the expression refers.

expr : str

The subexpression itself.

device : Device

The device responsible for the memory access.

dtype : dtype, optional

The dtype used for the expression. Defaults to core.default_float_dtype.

scalar: bool, optional :

Whether this is an expression only referring to scalar variables. Defaults to False

Attributes

 device The Device responsible for memory access expr The expression defining the subexpression identifiers The identifiers used in the expression

Methods

 get_addressable_value(name, group) Get the value (without units) of this variable in a form that can be indexed in the context of a group. get_addressable_value_with_unit(name, group) Get the value (with units) of this variable in a form that can be indexed in the context of a group.

Details

device

The Device responsible for memory access

expr

The expression defining the subexpression

identifiers

The identifiers used in the expression

get_addressable_value(name, group)[source]

Get the value (without units) of this variable in a form that can be indexed in the context of a group. For example, if a postsynaptic variable x is accessed in a synapse S as S.x_post, the synaptic indexing scheme can be used.

Parameters

name : str

The name of the variable

group : Group

The group providing the context for the indexing. Note that this group is not necessarily the same as Variable.owner: a variable owned by a NeuronGroup can be indexed in a different way if accessed via a Synapses object.

Returns

variable : object

The variable in an indexable form (without units).

get_addressable_value_with_unit(name, group)[source]

Get the value (with units) of this variable in a form that can be indexed in the context of a group. For example, if a postsynaptic variable x is accessed in a synapse S as S.x_post, the synaptic indexing scheme can be used.

Parameters

name : str

The name of the variable

group : Group

The group providing the context for the indexing. Note that this group is not necessarily the same as Variable.owner: a variable owned by a NeuronGroup can be indexed in a different way if accessed via a Synapses object.

Returns

variable : object

The variable in an indexable form (with units).