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/* Copyright 2002 by Jeffrey Chang. All rights reserved.
* This code is part of the Biopython distribution and governed by its
* license. Please see the LICENSE file that should have been included
* as part of this package.
*
* cdistancemodule.c
* Created 12 Jan 2002
*
* Optimized C routines that complement distance.py.
*/
#include "Python.h"
#include <math.h>
#include "csupport.h"
/* Functions in this module. */
static char cdistance_euclidean__doc__[] =
"euclidean(x, y) -> euclidean distance between x and y";
static PyObject *
cdistance_euclidean(PyObject *self, PyObject *args)
{
int i;
int length;
PyObject *py_x, *py_y;
PyObject *py_fastx, *py_fasty;
PyObject *py_xi, *py_yi;
double xi, yi;
double sum;
/* This could be optimized a lot more if I operated on the Numeric
* Array directly. However, that would seriously compromise the
* module's portability...
*/
if(!PyArg_ParseTuple(args, "OO", &py_x, &py_y))
return NULL;
length = PySequence_Size(py_x);
if(length < 0)
return NULL;
if(length != PySequence_Size(py_y)) {
PyErr_SetString(PyExc_ValueError, "vectors must be same length");
return NULL;
}
if(!(py_fastx = PySequence_Fast(py_x, "could not get fast sequence")))
return NULL;
if(!(py_fasty = PySequence_Fast(py_y, "could not get fast sequence"))) {
Py_DECREF(py_fastx);
return NULL;
}
sum = 0.0;
for(i=0; i<length; i++) {
py_xi = PySequence_Fast_GET_ITEM(py_fastx, i);
py_yi = PySequence_Fast_GET_ITEM(py_fasty, i);
xi = PyNumber_AsDouble(py_xi);
yi = PyNumber_AsDouble(py_yi);
if(PyErr_Occurred())
break;
sum += pow(xi-yi, 2.0);
}
Py_DECREF(py_fastx);
Py_DECREF(py_fasty);
if(PyErr_Occurred())
return NULL;
return PyFloat_FromDouble(sqrt(sum));
}
/* Module definition stuff */
static PyMethodDef cdistanceMethods[] = {
{"euclidean", cdistance_euclidean, METH_VARARGS,
cdistance_euclidean__doc__},
{NULL, NULL}
};
static char cdistance__doc__[] =
"XXX document here\n\
\n\
";
void initcdistance(void)
{
(void) Py_InitModule3("cdistance", cdistanceMethods, cdistance__doc__);
}
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