[SciPy-user] Pros and Cons of Python verses other array environments

Otto Tronarp otto at tronarp.se
Fri Sep 29 03:47:32 CDT 2006


Quoting Bill Baxter <wbaxter at gmail.com>:

> On 9/29/06, Otto Tronarp <otto at tronarp.se> wrote:
>> This touches the subject of inconsistency with math.add as one
>> example. One of my "favorite" peeve's is how the size (shape) is given
>> to functions that generate matrices. In some functions the size is
>> given as a tuple, in other the size in different dimensions are given
>> as seperate arguments. Here are some examples:
>>
>> To to create an array with shape M, N you do:
>> zeros((M, N))
>> ones((M, N))
>> rand(M, N)
>> eye(M, N)
>>
>> I'm sure more examples exists.
>
> Yep,
>     repmat(A,M,N)
> is another one.
> http://projects.scipy.org/scipy/numpy/ticket/292
>
> But I think you'll find that rand at least is no longer there.
> Instead you're supposed to use random.random((M,N))
>
> eye(M,N) is considered to be ok, because 1-D eye is pretty useless,
> and it's not clear what you'd want out of N-D identity matrix.

That is valid point, but I would still argue for unified use of shape  
args. Assume that I have a function that does some calculations on a  
matrix and adds another like this:

def foo(A, mxCreateFunc):
     # do some stuff with A
     return A + mxCreateFunc(A.shape)

If we hade unified shape args I could do
foo(A, random) # Add some noice
foo(A, zeros # Don't add nocie
foo(A, eye) # ??

I must admitt that I don't have any real world use cases for eye at  
hand, but I'm sure they are out there...

Otto

>
> There has been a lot of discussion about trying to unify on shape args
> always being tuples.
>
> --bb
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