a question about numpy

rechard rechardchen at gmail.com
Thu Sep 10 03:46:46 CEST 2009


Robert Kern wrote:
> On 2009-09-08 20:45 PM, hi_roger wrote:
>> hello, i want to ask a question about numpy.
>>
>> i know how to select a submatrix using the slice object in numpy. But
>> how can i select a submatrix
>> A[i1,i2,i3;j1,j2,j3] (elements in A on line i1,i2,i3 and column
>> j1,j2,j3 ,  and i1,i2,i3,j1,j2,j3 are all arbitrary numbers )
>> The submatrix must share data memory with original matrix.
>>
>> Any one help? thank you
> 
> Sturla is almost correct. What you really want is this:
> 
>   i = [[i1], [i2], [i3]]
>   j = [[j1, j2, j3]]
>   B = A[i, j]
> 
> http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html#integer
> 
> If you have more numpy questions, please ask on the numpy mailing list.
> 
>   http://www.scipy.org/Mailing_Lists
> 
wow...,  thank you all :)
but it seems it is impossible to make the submatrix share data with the 
original matrix in pure numpy code ?



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