# ArrayVariable class¶

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

class brian2.core.variables.ArrayVariable(name, owner, size, device, dimensions=Dimension(), dtype=None, constant=False, scalar=False, read_only=False, dynamic=False, unique=False)[source]

An object providing information about a model variable stored in an array (for example, all state variables). Most of the time Variables.add_array should be used instead of instantiating this class directly.

Parameters

name : ‘str’

The name of the variable. Note that this refers to the original name in the owning group. The same variable may be known under other names in other groups (e.g. the variable v of a NeuronGroup is known as v_post in a Synapse connecting to the group).

dimensions : Dimension, optional

The physical dimensions of the variable

owner : Nameable

The object that “owns” this variable, e.g. the NeuronGroup or Synapses object that declares the variable in its model equations.

size : int

The size of the array

device : Device

The device responsible for the memory access.

dtype : dtype, optional

The dtype used for storing the variable. If none is given, defaults to core.default_float_dtype.

constant : bool, optional

Whether the variable’s value is constant during a run. Defaults to False.

scalar : bool, optional

Whether this array is a 1-element array that should be treated like a scalar (e.g. for a single delay value across synapses). Defaults to False.

Whether this is a read-only variable, i.e. a variable that is set internally and cannot be changed by the user. Defaults to False.

unique : bool, optional

Whether the values in this array are all unique. This information is only important for variables used as indices and does not have to reflect the actual contents of the array but only the possibility of non-uniqueness (e.g. synaptic indices are always unique but the corresponding pre- and post-synaptic indices are not). Defaults to False.

Attributes

 conditional_write Another variable, on which the write is conditioned (e.g. device The Device responsible for memory access. size The size of this variable. unique Wether all values in this arrays are necessarily unique (only relevant for index variables).

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. Get the length of the value associated with the variable or 0 for a scalar variable. Return the value associated with the variable (without units). set_value(value) Set the value associated with the variable.

Details

conditional_write

Another variable, on which the write is conditioned (e.g. a variable denoting the absence of refractoriness)

device

The Device responsible for memory access.

size

The size of this variable.

unique

Wether all values in this arrays are necessarily unique (only relevant for index variables).

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).

get_len()[source]

Get the length of the value associated with the variable or 0 for a scalar variable.

get_value()[source]

Return the value associated with the variable (without units). This is the way variables are accessed in generated code.

set_conditional_write(var)[source]
set_value(value)[source]

Set the value associated with the variable.