Re: [Numpy-discussion] partial_sum/adj_difference?
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 [EMAIL PROTECTED] 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 ___ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
[Numpy-discussion] partial_sum/adj_difference?
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
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Re: [Numpy-discussion] partial_sum/adj_difference?
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
-
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Re: [Numpy-discussion] partial_sum/adj_difference?
-Original Message-
From: [EMAIL PROTECTED] on behalf of Francesc Altet
Instead of
for i in range(len(a)): ps[i] = a[:i].sum()
use
a.cumsum()
Nadav
Sent: Tue 19-Feb-08 20:59
To: Discussion of Numerical Python
Subject: Re: [Numpy-discussion] partial_sum/adj_difference?
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
-
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Re: [Numpy-discussion] partial_sum/adj_difference?
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.
adj_diff[i] = x[i] - x[i-1] : i 1, x[i] otherwise
numpy.diff
Regards
Stéfan
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Re: [Numpy-discussion] partial_sum/adj_difference?
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])
signature.asc
Description: Digitaalisesti allekirjoitettu viestin osa
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Re: [Numpy-discussion] partial_sum/adj_difference?
On Feb 19, 2008 11:38 AM, Neal Becker [EMAIL PROTECTED] wrote: 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. There's also numpy.diff, and the little known numpy.ediff1d x=numpy.arange(10) numpy.ediff1d(x,to_begin=0) array([0, 1, 1, 1, 1, 1, 1, 1, 1, 1]) ___ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] partial_sum/adj_difference?
On Feb 19, 2008 12:41 PM, Stefan van der Walt [EMAIL PROTECTED] 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
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Re: [Numpy-discussion] partial_sum/adj_difference?
On Tue, 19 Feb 2008 13:50:04 -0700
Charles R Harris [EMAIL PROTECTED] wrote:
On Feb 19, 2008 12:41 PM, Stefan van der Walt
[EMAIL PROTECTED] 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
;-)
from numpy import cumprod
help (cumprod)
Nils
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Re: [Numpy-discussion] partial_sum/adj_difference?
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 ___ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] partial_sum/adj_difference?
On Feb 19, 2008 2:20 PM, Stefan van der Walt [EMAIL PROTECTED] 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. Chuck ___ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
