["python","arrays","numpy","boolean","numpy-ndarray"]
How do I create a numpy array of all True or all False?

In Python, how do I create a numpy array of arbitrary shape filled with all True or all False?
The answer: numpy.full((2, 2), True) Explanation: numpy creates 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 to the dtype of the second parameter, so we can just write: numpy.full((2, 2), True)