[Numpy-discussion] Should bool_ subclass int?
Alan G Isaac
aisaac@american....
Mon Jul 9 17:48:52 CDT 2007
On Mon, 9 Jul 2007, Timothy Hochberg apparently wrote:
> Why not simply use & and | instead of + and *?
A couple reasons, none determinative.
1. numpy is right a Python is wrong it this case
(but granted, I would usually go with Python is such cases)
2. consistency with Boolean matrices
Elaboration on 2:
Boolean matrices currently behave as expected, with standard
notation. Related to this, they handle exponents correctly.
Suppose arrays are changed as you suggest.
Then either
- array behavior and matrix behavior are decoupled, or
- matrix behavior is completely broken for boolen matrices
Alan Isaac
PS Examples of good behavior:
>>> x
matrix([[True, True],
[True, False]], dtype=bool)
>>> y
matrix([[False, True],
[True, False]], dtype=bool)
>>> x*y
matrix([[True, True],
[False, True]], dtype=bool)
>>> x**2
matrix([[True, True],
[True, True]], dtype=bool)
>>>
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