[Numpy-discussion] untenable matrix behavior in SVN

Christopher Barker Chris.Barker@noaa....
Tue Apr 29 16:49:22 CDT 2008


Keith Goodman wrote:
> It would seem odd to me if x[i,:]
>  returned different types of objects based on the type of i:

I think this is where matrices should act like arrays:

 >>> a
array([[0, 1, 2],
        [3, 4, 5],
        [6, 7, 8]])
 >>> a[:,[1]]
array([[1],
        [4],
        [7]])
 >>> a[:,1]
array([1, 4, 7])

in this case, it's not really different types, but totally different 
concepts -- indexing with a sequence is different than a scalar, just 
like indexing with a slice is different than a scalar.

There are many, many places in python code where we have to make 
distinctions between a single object and a sequence of objects that 
happens to be of length one.

-Chris

-- 
Christopher Barker, Ph.D.
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