[SciPy-user] Array functions
Robert Kern
rkern at ucsd.edu
Mon Aug 8 06:21:19 CDT 2005
Howey, David A wrote:
> I guess this is a numpy question, but how do I do truth tests on arrays?
> I'm trawling around the documentation but struggling to find an answer..
>
> I want to test if any array contains ONLY zeros.
>
> Originally I had:
> if a == 0:
> # code in here
>
> I need this to be true both for
> a = 0 # ie a is just a number
>
> and for
> a = array((0,0,0,0,0))
>
> It must return false for any array with any nonzero elements anywhere
In [1]: a = array((0,0,0,0,0))
In [2]: alltrue(a == 0)
Out[2]: 1
In [3]: a == 0
Out[3]: array([1, 1, 1, 1, 1],'b')
In [4]: a[1] = 10
In [5]: alltrue(a == 0)
Out[5]: 0
In [6]: a == 0
Out[6]: array([1, 0, 1, 1, 1],'b')
There's also a sometrue() function, too.
--
Robert Kern
rkern at ucsd.edu
"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter
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