[Numpy-discussion] I hate for loops

Charles R Harris charlesr.harris@gmail....
Fri Jun 8 22:19:19 CDT 2007


On 6/8/07, Mathew Yeates <mathewww@charter.net> wrote:
>
> Hi
> I'm looking for a more elegant way of setting my array elements
> Using "for" loops it would be
> for i in range(rows):
>     for j in range(cols):
>        N[i,j] = N[i-1][j] + N[i][j-1] - N[i-1][j-1]


If the initial values of the recursion are in the first row and column you
can use the result: N[i,j] = N[0,j] + N[i,0]. It's like the PDE D_xD_y N = 0
whose solution is the sum of two functions f(x) + g(y). It gets more
complicated if you are looking for a more general result.

Chuck
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