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I have a n x n matrix in numpy which has 0 and non-0 values. Is there a way to easily convert it to a boolean matrix?
Thanks.
572
A boolean array can be created manually by using dtype=bool when creating the array. Values other than 0 , None , False or empty strings are considered True. Alternatively, numpy automatically creates a boolean array when comparisons are made between arrays and scalars or between arrays of the same shape.
A boolean array can be made using dtype=bool, manually. All values other than '0', 'False', 'None', or empty strings are considered True in a boolean array.
We can also index NumPy arrays using a NumPy array of boolean values on one axis to specify the indices that we want to access. This will create a NumPy array of size 3x4 (3 rows and 4 columns) with values from 0 to 11 (value 12 not included).
numpy.array(old_matrix, dtype=bool)
Alternatively,
old_matrix != 0
The first version is an elementwise coercion to boolean. Analogous constructs will work for conversion to other data types. The second version is an elementwise comparison to 0. It involves less typing, but ran slightly slower when I timed it. Which you use is up to you; I'd probably decide based on whether "convert to boolean" or "compare to 0" is a better conceptual description of what I'm after.
169
You should use array.astype(bool) (or array.astype(dtype=bool)). Works with matrices too.
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