How to create a numpy array of all True or all False?
numpy already allows the creation of arrays of all ones or all zeros very easily:
e.g. numpy.ones((2, 2))
or numpy.zeros((2, 2))
Since True
and False
are represented in Python as 1
and 0
, respectively, we have only to specify this array should be boolean using the optional dtype
parameter and we are done.
numpy.ones((2, 2), dtype=bool)
returns:
array([[ True, True],
[ True, True]], dtype=bool)
UPDATE: 30 October 2013
Since numpy version 1.8, we can use full
to achieve the same result with syntax that more clearly shows our intent (as fmonegaglia points out):
numpy.full((2, 2), True, dtype=bool)
UPDATE: 16 January 2017
Since at least numpy version 1.12, full
automatically casts results to the dtype
of the second parameter, so we can just write:
numpy.full((2, 2), True)
numpy.full((2,2), True, dtype=bool)
ones
and zeros
, which create arrays full of ones and zeros respectively, take an optional dtype
parameter:
>>> numpy.ones((2, 2), dtype=bool)
array([[ True, True],
[ True, True]], dtype=bool)
>>> numpy.zeros((2, 2), dtype=bool)
array([[False, False],
[False, False]], dtype=bool)