[Numpy-discussion] I hate for loops
Charles R Harris
charlesr.harris at gmail.com
Fri Jun 8 23:21:59 EDT 2007
On 6/8/07, Charles R Harris <charlesr.harris at gmail.com> wrote:
> On 6/8/07, Mathew Yeates <mathewww at 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.
Make that N[i,j] = N[0,j] + N[i,0] - N[0,0].
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