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Thomas Haslwanter | 29 Jul 2012 14:23
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Contributing to SciPy?

Hi,
I found an error on the SciPy Cookbook (described below), and wanted to fix it.
So I wrote a corrected version and a unittest procedure. But now I don't know
how I can submit/contribute it to SciPy. (BTW, the wiki did not let me to change
it, even after I registered.) Is the only way to pull the whole sourcecode,
install Fortran and C++ compilers, etc? Or can I just submit Python code?
Please let me know.

The problem:
 The Cookbook entry
 http://www.scipy.org/Cookbook/SavitzkyGolay
 has a number of problems:

 1) As it is, it does in general not run. The line
    "import numpy as np"
 should be inserted before the first "try" in line 49

 2) I don't completely understand the workings of the code. However, when
 you put in a sine-wave and calculate the first derivative,     you get out
 a negative(!) cosine - not a cosine. The correct result appears if you
 replace "m," in line 68 with "m[::-1],"

 Since the Savitzky-Golay filter is a very commonly used filter, I regard
 this mistake as significant.

thomas
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Ralf Gommers | 4 Aug 2012 13:06
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Re: Contributing to SciPy?



On Sun, Jul 29, 2012 at 2:23 PM, Thomas Haslwanter <thomas.haslwanter <at> alumni.ethz.ch> wrote:
Hi,
I found an error on the SciPy Cookbook (described below), and wanted to fix it.
So I wrote a corrected version and a unittest procedure. But now I don't know
how I can submit/contribute it to SciPy. (BTW, the wiki did not let me to change
it, even after I registered.)

That's odd. Can other people edit that page (I can)?
 
Is the only way to pull the whole sourcecode,
install Fortran and C++ compilers, etc? Or can I just submit Python code?
Please let me know.

The Cookbook isn't part of the SciPy source code, so in this case the only way is to edit the wiki page. Or open a ticket as you did: http://projects.scipy.org/scipy/ticket/1706

If your question is how you would go about adding this function in scipy.signal, which as I noted on #1706 was discussed before, you can attach patches to Trac. The better way (i.e. lower overhead for scipy devs) would indeed be to use git and send a pull request. How to do that is described at https://github.com/scipy/scipy/blob/master/HACKING.rst.txt.

Ralf


The problem:
 The Cookbook entry
 http://www.scipy.org/Cookbook/SavitzkyGolay
 has a number of problems:

 1) As it is, it does in general not run. The line
    "import numpy as np"
 should be inserted before the first "try" in line 49

 2) I don't completely understand the workings of the code. However, when
 you put in a sine-wave and calculate the first derivative,     you get out
 a negative(!) cosine - not a cosine. The correct result appears if you
 replace "m," in line 68 with "m[::-1],"

 Since the Savitzky-Golay filter is a very commonly used filter, I regard
 this mistake as significant.

thomas

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