[Matrix-SIG] coding examples/advice for building Numeric Python extensions?

[Joe Van Andel]

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I'm starting a new project to build a Doppler radar timeseries processing 
environment using NumPy.  Perhaps I've missed something, but I haven't 
found any documentation that explains how to write my own extension.  
I've written the argument handling code by adding some new SWIG templates 
(attached)

Now that I'm writing the body of my functions, I've got some questions:

1) When (if ever) I should be concerned about "non-contiguous" arrays.

2) If I want to avoid the overhead of copying megabytes of data to insure 
that it is contiguous, how do I access the data in the PyArrayObject?

3) Has someone who is familiar with NumPy written a brief extension writer's guide?  

4) At the very least, could someone write somes brief descriptions of the 
functions that an extension writer should be using?

5) Can someone recommend a short NumPy extension that would serve as an 
example?

(IMHO, I think more people might starting using NumPy if there was 
documentation of how to write extensions. )

Thanks much for your help!


Joe VanAndel  		Internet: vanandel@ucar.edu
National Center for	http://www.atd.ucar.edu/~vanandel/home.html
Atmospheric Research


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Content-Description: numpy_typemaps.i

%typemap(python,in) PyArrayObject *INPUT
{
    $target = (PyArrayObject *)$source;    
}

%typemap(python,in) PyArrayObject *INPUT_1D
{
    $target = (PyArrayObject *)$source;    
    if ($target->nd != 1) {
        PyErr_SetString(PyExc_TypeError, "must be 1D array");
        return NULL;
    }
}

%typemap(python,in) PyArrayObject *INPUT_2D
{
    $target = (PyArrayObject *)$source;    
    if ($target->nd != 2) {
    //	printf("%s: num dim = %d\n", "$target", $target->nd);
        PyErr_SetString(PyExc_TypeError, "must be 2D array");
        return NULL;
    }
}


%typemap(python,out) PyObject * {
    $target = $source;
}

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