[Numpy-discussion] Response to PEP suggestions

Jeff Whitaker jswhit at fastmail.fm
Thu Feb 17 12:14:16 CST 2005


Travis Oliphant wrote:

>
> 2) Multidimensional array indexing.
>
> Sometimes it is useful to select out of an array some elements based 
> on it's linear (flattened) index in the array.   MATLAB, for example, 
> will allow you to take a three-dimensional array and index it with a 
> single integer based on it's Fortran-order:  x(1,1,1),  x(2,1,1), ...
>
> What I'm proposing would have X[K] essentially equivalent to X.flat[K].  

Maybe I'm missing something, but in Numeric and Numarray right now

 >>> from Numeric import *
 >>> a = reshape(arange(9),(3,3))
 >>> print a
[[0 1 2]
 [3 4 5]
 [6 7 8]]
 >>> a[1]
array([3, 4, 5])
 >>> a.flat[1]
1

so a[K] and a.flat[K] are very different things for multidimensional 
arrays.  I think it would be a bad idea to change this now - it would 
certainly break a lot of my code.

Or are you only talking about the case when K is a rank-1 index array 
and not a scalar?

-Jeff


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Jeffrey S. Whitaker         Phone  : (303)497-6313
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