Re: [Matplotlib-users] example of pareto chart

[Benjamin R. <ben...@ou...>]

On Wed, Sep 26, 2012 at 4:31 AM, Pierre Haessig <pie...@cr...>wrote:

>  Hi,
>
> Just a detail :
>
> Le 26/09/2012 04:29, Paul Tremblay a écrit :
>
> percent = (np.divide(the_cumsum, the_sum)) * 100
>
> This lines doesn't work on my computer (numpy 1.6.2)
>
> Indeed, there is a casting issue :
> In [2]: percent
> Out[2]: array([  0,   0,   0,   0, 100])
>
> However, using the regular "/" operator instead of np.divide gives the
> proper result:
> In [8]: the_cumsum/the_sum*100
> Out[8]: array([  42.10526316,   71.05263158,   90.78947368,   97.36842105,
> 100.        ])
>
> Best,
> Pierre
>
>
Actually, if you are using the latest numpy (the 1.7 beta), that will also
not work unless you are using py3k or did "from __future__ import
division".  Well, actually, using np.divide will always result in integer
division (this may or may not be a bug).

The correct thing to do until we move on to py3k with its "true division"
is to make sure we cast one of the operands as floats:
the_sum.astype('f').  Plus, using '/' is more concise and readable.

Cheers!
Ben Root