The return shape has dimensions python code many other uses

and cumprod methods of arrays. The following Python code implements an

equivalent of the accumulate method.

This method is a generalization of both reduce and accumulate. It offers the

ability to reduce along an axis but only between certain indices. The indices input must be a one dimensional (index) sequence. Then, if Ik is the kthele-ment of indices, the reduceat method computes <op>.reduce(array[Ik:Ik+1]).

Equivalent Python code is� �� �

>>> i1 = [index exp[:]]*array.ndim
>>> i2 = [index exp[:]]*array.ndim
>>> outshape = list(array.shape)
>>> N = array.shape[axis]
>>> outshape[axis] = len(indices)
>>> result = zeros(outshape, dtype or array.dtype) >>> for k,Ik in enumerate(indices):
i1[axis] = k ...

Example: Suppose a is a two-dimensional array of shape 10 × 20. Then, res=add.reduce (a, [0,3,1]) returns a 3 × 20 array with res[0,:] = add.reduce(a[:,0:3]), res[1,:] = a[:,3], and res[2,:] = add.reduce(a[:,1:]).

9.4.4 Outer

Among many other uses, arithmetic tables can be conveniently built using outer:

>>> multiply.outer([1,7,9,12],arange(5,12))

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