[Numpy-discussion] Strange behavior of operator *=

[Matthieu Brucher]

Indeed, it is not. In the first case, you keep your original object and each
(integer) element is multiplied by 1.0. In the second example, you are
creating a temporary object a*x, and as x is a float and a an array of
integers, the result will be an array of floats, which will be assigned to
a.

Matthieu

2011/4/5 François Steinmetz <francois.steinmetz at gmail.com>

> Hi all,
>
> I have encountered the following strangeness :
> >>> from numpy import *
> >>> __version__
> '1.5.1'
> >>> a = eye(2, dtype='int')
> >>> a *= 1.0
> >>> a ; a.dtype
> array([[1, 0],
>        [0, 1]])
> dtype('int64')
> >>> a = a * 1.0
> >>> a ; a.dtype
> array([[ 1.,  0.],
>        [ 0.,  1.]])
> dtype('float64')
>
> So, in this case "a *= x" is not equivalent to "a = a*x" ?
>
> François
>
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>


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