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[Python-Dev] Pre-PEP: Allow Empty Subscript List Without Parentheses

Alex Martelli aleaxit at gmail.com
Sat Jun 10 05:25:31 CEST 2006 
On Jun 9, 2006, at 4:55 PM, Greg Ewing wrote:
    ...
> Think about how you get from an N dimensional array to
> an N-1 dimensional array: you index it, e.g.
>
>   A2 = [[1, 2], [3, 4]] # a 2D array
>
>   A1 = A2[1] # a 1D array
>
>   A0 = A1[1] # a 0D array???
>
>   print A0
>
> What do you think this will print?

Don't confuse arrays with lists...:

 >>> A2 = Numeric.array([[1, 2], [3, 4]], Numeric.Float32)
 >>> A1 = A2[1]
 >>> A0 = A1[1]
 >>> type(A0)
<type 'array'>
 >>>

It doesn't work the same if you specify Numeric.Float64 instead -- an  
ancient wart of Numeric, of course.  Still, Numeric and its  
descendants are "the" way in Python to get multi-dimensional arrays,  
since the stdlib's array module only supports one-dimensional ones,  
and lists are not arrays.


Alex
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