A Tuesday 19 February 2008, Neal Becker escrigué:

Does numpy/scipy have a partial_sum and adj_difference function?

partial_sum[i] = \sum_{j=0}^{i} x[j] adj_diff[i] = x[i] - x[i-1] : i > 1, x[i] otherwise

I don't know, but by using views the next should be fairly efficient: # Partial sum In [28]: a = numpy.arange(10) In [29]: ps = numpy.empty(len(a), 'int') In [30]: for i in range(len(a)): ps[i] = a[:i].sum() ....: In [31]: ps Out[31]: array([ 0, 0, 1, 3, 6, 10, 15, 21, 28, 36]) # Adj difference: In [35]: ad = numpy.empty(len(a), 'int') In [36]: ad[0] = a[0] In [37]: ad[1:] = a[1:] - a[:-1] In [38]: ad Out[38]: array([0, 1, 1, 1, 1, 1, 1, 1, 1, 1]) Cheers, --

0,0< Francesc Altet     http://www.carabos.com/ V V Cárabos Coop. V.   Enjoy Data "-"

On Feb 19, 2008 11:38 AM, Neal Becker wrote:

Does numpy/scipy have a partial_sum and adj_difference function?

partial_sum[i] = \sum_{j=0}^{i} x[j]

Make add.accumulate will do the trick: In [1]: add.accumulate(arange(10)) Out[1]: array([ 0, 1, 3, 6, 10, 15, 21, 28, 36, 45]) In [3]: arange(10).cumsum() Out[3]: array([ 0, 1, 3, 6, 10, 15, 21, 28, 36, 45])

adj_diff[i] = x[i] - x[i-1] : i > 1, x[i] otherwise

Well, x[1:] - x[:-1] will give the usual differences. If you need the leading x[0] prefix the x vector with a 0. In [4]: a = arange(10) In [5]: b = a[1:] - a[:-1] In [6]: b Out[6]: array([1, 1, 1, 1, 1, 1, 1, 1, 1]) Chuck

ti, 2008-02-19 kello 13:38 -0500, Neal Becker kirjoitti:

Does numpy/scipy have a partial_sum and adj_difference function?

partial_sum[i] = \sum_{j=0}^{i} x[j] adj_diff[i] = x[i] - x[i-1] : i > 1, x[i] otherwise

cumsum and diff do something like this:

...

...

import numpy a = [1,2,3,4,5,3,1] numpy.cumsum(a) array([ 1, 3, 6, 10, 15, 18, 19]) numpy.diff(a) array([ 1, 1, 1, 1, -2, -2])

On Feb 19, 2008 12:41 PM, Stefan van der Walt wrote:

Hi Neal

On Tue, Feb 19, 2008 at 01:38:06PM -0500, Neal Becker wrote:

...

Does numpy/scipy have a partial_sum and adj_difference function?

partial_sum[i] = \sum_{j=0}^{i} x[j]

numpy.cumsum

Yikes, the docstring contains "Blah, blah". I'll fix that immediately.

Gosh, And here I thought you were going to fix that. Deleting the "blahs" isn't a fix, it's a coverup. Now there is no extended documentation at all. Chuck

On Tue, Feb 19, 2008 at 01:50:04PM -0700, Charles R Harris wrote:

And here I thought you were going to fix that. Deleting the "blahs" isn't a fix, it's a coverup. Now there is no extended documentation at all.

I wouldn't call "Blah, blah" extended documentation -- in fact, I would've been rather embarrassed if that showed up on my screen during a workshop. "Blah, blah" also doesn't strike me as the ideal TODO marker. We can maybe use some more sensible text, or write a decorator to mark these functions. I'd say we add them to the TODO list for the next doc-day and run with it... Regards Stéfan

On Tue, Feb 19, 2008 at 05:36:52PM -0700, Charles R Harris wrote:

On Feb 19, 2008 2:20 PM, Stefan van der Walt wrote:

On Tue, Feb 19, 2008 at 01:50:04PM -0700, Charles R Harris wrote: > And here I thought you were going to fix that. Deleting the > "blahs" isn't a > fix, it's a coverup. Now there is no extended > documentation at all.

I wouldn't call "Blah, blah" extended documentation -- in fact, I would've been rather embarrassed if that showed up on my screen during a workshop.

"Blah, blah" also doesn't strike me as the ideal TODO marker. We can maybe use some more sensible text, or write a decorator to mark these functions.

It has certainly been effective in practice.

Yes, ironically :) http://projects.scipy.org/scipy/numpy/changeset/4813 http://projects.scipy.org/scipy/numpy/changeset/4814 The first courtesy of Matthew Brett. Regards Stéfan