[Numpy-discussion] where() on mac/pc return different things
James Battat
jbattat@cfa.harvard....
Wed Jan 23 17:32:06 CST 2008
Hi,
numpy.where() returns different things on my windowsXP machine than on my
collaborator's mac osx machine.
For example, consider:
>>> import numpy
>>> a = numpy.array([1,2,3,4])
>>> b = numpy.where( a > 2 )
On WindowsXP (python 2.4.2, numpy 1.0.1), I get:
>>> print b
(array([2, 3]), )
>>> print b[0]
[2 3]
While in OSX (python 2.4.3, numpy 0.9.6), he gets:
>>> print b
[2, 3]
>>> print b[0]
2
This matters because we use where() to get indices to loop over. On the
mac you can then loop through the b array:
for item in b:
if b > 5:
print 'hi'
But this approach fails on a pc because:
if b > 5:
>>> ValueError: The truth value of an array with more than one element
>>> is ambiguous. Use a.any() or a.all()
I'd like to avoid having to do:
if mac:
b = numpy.where( a > 5)
if pc:
b = numpy.where( a > 5)[0]
Has anybody else notice dealt with this? Is this a mac/pc difference or a
numpy 1.01 vs. numpy 0.9.6 difference?
Thanks for the help,
James
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