# get_or_create_dimension function¶

(Shortest import: from brian2 import get_or_create_dimension)

brian2.units.fundamentalunits.get_or_create_dimension(*args, **kwds)[source]

Create a new Dimension object or get a reference to an existing one. This function takes care of only creating new objects if they were not created before and otherwise returning a reference to an existing object. This allows to compare dimensions very efficiently using is.

Parameters: args : sequence of float A sequence with the indices of the 7 elements of an SI dimension. kwds : keyword arguments a sequence of keyword=value pairs where the keywords are the names of the SI dimensions, or the standard unit.

Notes

The 7 units are (in order):

Length, Mass, Time, Electric Current, Temperature, Quantity of Substance, Luminosity

and can be referred to either by these names or their SI unit names, e.g. length, metre, and m all refer to the same thing here.

Examples

The following are all definitions of the dimensions of force

>>> from brian2 import *
>>> get_or_create_dimension(length=1, mass=1, time=-2)
metre * kilogram * second ** -2
>>> get_or_create_dimension(m=1, kg=1, s=-2)
metre * kilogram * second ** -2
>>> get_or_create_dimension([1, 1, -2, 0, 0, 0, 0])
metre * kilogram * second ** -2