mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-27 21:53:30 +08:00
Johannes Schönberger
56 lines
1.6 KiB
Cython
56 lines
1.6 KiB
Cython
#cython: cdivision=True
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#cython: boundscheck=False
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#cython: nonecheck=False
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#cython: wraparound=False
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cdef inline unsigned char point_in_polygon(Py_ssize_t nr_verts, double *xp,
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double *yp, double x,
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double y) nogil:
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"""Test whether point lies inside a polygon.
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Parameters
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----------
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nr_verts : int
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Number of vertices of polygon.
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xp, yp : double array
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Coordinates of polygon with length nr_verts.
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x, y : double
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Coordinates of point.
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"""
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cdef Py_ssize_t i
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cdef unsigned char c = 0
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cdef Py_ssize_t j = nr_verts - 1
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for i in range(nr_verts):
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if (
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(((yp[i] <= y) and (y < yp[j])) or
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((yp[j] <= y) and (y < yp[i])))
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and (x < (xp[j] - xp[i]) * (y - yp[i]) / (yp[j] - yp[i]) + xp[i])
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):
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c = not c
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j = i
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return c
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cdef void points_in_polygon(Py_ssize_t nr_verts, double *xp, double *yp,
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Py_ssize_t nr_points, double *x, double *y,
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unsigned char *result) nogil:
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"""Test whether points lie inside a polygon.
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Parameters
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----------
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nr_verts : int
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Number of vertices of polygon.
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xp, yp : double array
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Coordinates of polygon with length nr_verts.
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nr_points : int
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Number of points to test.
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x, y : double array
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Coordinates of points.
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result : unsigned char array
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Test results for each point.
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"""
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cdef Py_ssize_t n
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for n in range(nr_points):
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result[n] = point_in_polygon(nr_verts, xp, yp, x[n], y[n])
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