On 25 Oct 2004, at 18:19, Stephen Walton wrote:
On Mon, 2004-10-25 at 10:26 +0200, Peter Verveer wrote:
On 25 Oct 2004, at 04:17, Stephen Walton wrote:
I don't think we need sumall. The methods and the functions should simply work the same way. If one wants sumall, use A.flat.sum() or, if you can't use the methods or attributes on your old version of Python, sum(ravel(A)).
I think this may be inefficient, because ravel and flat may make a copy of the data. Also I think using flat/ravel in such a way is plain ugly and a complex way to do it.
You may be right about the copying, I couldn't say. I don't think sum(ravel(A)) looks any worse than sum(sum(sum(A))) for a rank 3 array, but ugly is in the eye of the beholder.
It does not look worse, I agree with that! But I would argue it should have been sum(A) in the first place to sum over al axes... The sumall would not have been needed, and summing over one (or a sub-set) axis could have been implemented as a an optional argument to sum().
In my opinion functions that calculate a statistic like sum should return the total in the first place, rather then over a single axis.
It depends on the data. I use rank-2 arrays which are images and are therefore homogeneous. Even there, though, I often want the sum of all rows or all columns. For heterogeneous data (e.g., columns of different Y's as a function of X), the present sum() makes sense. In other words, we will always need ways to sum over just one dimension and over all dimensions. By analogy with MATLAB (I'm guessing), sum() in Numeric and numarray does a one-D sum.
I agree it is a useful feature, and it should still be possible to do that using an optional axis argument, even better I would love to be able to sum over several axes in one go, I find the one-dimensional character of reduce limiting, but I digress. In any case, I suppose we will stick with the current behaviour for backwards compatibility. Cheers, Peter