[Numpy-discussion] How operating arrays in a determined axis?

Aureli Soria Frisch Aureli.Soria_Frisch at ipk.fhg.de
Mon Mar 19 14:05:16 CST 2001


Hello again,

I have forgotten in my previous mail that I want the procedure to run
independent of the value of N... So the value of N is not known during the
implementation.

Sorry about the duplication...

>Hello!
>
>I have a N-dimensional array A and I want to operate in one of the axis
>(k) with a 1 dimensional array (for instance,  subtracting an array B of
>length k). I have looked for some solutions in the manual and did not
>found any.
>
>So after testing a lot I found following solution:
>
>A=Numeric.array(a)
>
>A.shape=(a1,a2,...,ak,...,aN)	#where N is any int value
>
>B=Numeric.array(b)
>B.shape=(ak,)
>
>
>A_modified=Numeric.reshape(A, (a1*a2*...*aN,ak)) #ak is not included in
>the product
>
>result=[]
>for i in A_modified:
>	result.append(i - B)
>
>
>and finally reshaping the result appropriately. But it does not seem
>neither elegant nor simple.
>
>Is there any more elegant solution? The key point is: how to operate a N-D
>array with a 1D in one determined axis?
>
>Thanks in advance.
>Regards,
>Aureli
>




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Aureli Soria Frisch
Fraunhofer IPK
Dept. Pattern Recognition

post: Pascalstr. 8-9, 10587 Berlin, Germany
e-mail:aureli at ipk.fhg.de
fon: +49 30 39 00 61 50
fax: +49 30 39 17 517
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