mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-30 04:19:36 +08:00
added draw.polygon function with test cases
This commit is contained in:
Johannes Schönberger
+93
-6
@@ -1,16 +1,18 @@
|
||||
import numpy as np
|
||||
import math
|
||||
from libc.stdlib cimport malloc, free
|
||||
cimport numpy as np
|
||||
cimport cython
|
||||
|
||||
cdef extern from "math.h":
|
||||
int abs(int i)
|
||||
cdef extern from "../morphology/_pnpoly.h":
|
||||
int pnpoly(int nr_verts, double *xp, double *yp,
|
||||
double x, double y)
|
||||
|
||||
@cython.boundscheck(False)
|
||||
@cython.wraparound(False)
|
||||
def bresenham(int y, int x, int y2, int x2):
|
||||
"""
|
||||
Generate line pixel coordinates.
|
||||
|
||||
"""Generate line pixel coordinates.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
y, x : int
|
||||
@@ -46,7 +48,7 @@ def bresenham(int y, int x, int y2, int x2):
|
||||
|
||||
rr = np.zeros(int(dx) + 1, dtype=np.int32)
|
||||
cc = np.zeros(int(dx) + 1, dtype=np.int32)
|
||||
|
||||
|
||||
for i in range(dx):
|
||||
if steep:
|
||||
rr[i] = x
|
||||
@@ -64,3 +66,88 @@ def bresenham(int y, int x, int y2, int x2):
|
||||
cc[dx] = x2
|
||||
|
||||
return rr, cc
|
||||
|
||||
@cython.boundscheck(False)
|
||||
@cython.wraparound(False)
|
||||
def _polygon_area(np.ndarray[np.double_t, ndim=1] x, np.ndarray[np.double_t, ndim=1] y):
|
||||
"""Calculate area of polygon.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
x : ndarray
|
||||
X coordinates of polygon
|
||||
y : ndarray
|
||||
Y coordinates of polygon
|
||||
|
||||
Returns
|
||||
-------
|
||||
area : double
|
||||
area of polygon
|
||||
"""
|
||||
cdef double area
|
||||
cdef int i
|
||||
cdef int j = x.shape[0]-1
|
||||
for i in xrange(x.shape[0]):
|
||||
area += (x[j]+x[i])*(y[j]-y[i])
|
||||
j = i
|
||||
return abs(0.5*area)
|
||||
|
||||
@cython.boundscheck(False)
|
||||
@cython.wraparound(False)
|
||||
def polygon(verts, shape=None):
|
||||
"""Generate coordinates of pixels within polygon.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
verts : Nx2 ndarray
|
||||
(row, col) coordinates
|
||||
shape : tuple, optional
|
||||
image shape which is used to determine maximum extents of output pixel
|
||||
coordinates. This is useful for polygons which exceed the image size,
|
||||
default None
|
||||
|
||||
Returns
|
||||
-------
|
||||
rr, cc : ndarray of int
|
||||
Pixel coordinates of polygon.
|
||||
May be used to directly index into an array, e.g.
|
||||
``img[rr, cc] = 1``.
|
||||
"""
|
||||
cdef int nr_verts = verts.shape[0]
|
||||
cdef int minr = <int>max(0, verts[:,0].min())
|
||||
cdef int maxr = <int>math.ceil(verts[:,0].max())
|
||||
cdef int minc = <int>max(0, verts[:,1].min())
|
||||
cdef int maxc = <int>math.ceil(verts[:,1].max())
|
||||
|
||||
# make sure output coordinates do not exceed image size
|
||||
if shape is not None:
|
||||
maxr = min(shape[0]-1, maxr)
|
||||
maxc = min(shape[1]-1, maxc)
|
||||
|
||||
cdef int r, c
|
||||
cdef int i = 0
|
||||
|
||||
#: make contigous arrays for r, c coordinates
|
||||
verts = verts.astype('double')
|
||||
cdef np.ndarray contiguous_rdata = verts[:,0].copy(order='C')
|
||||
cdef np.ndarray contiguous_cdata = verts[:,1].copy(order='C')
|
||||
cdef np.double_t* rptr = <np.double_t*>contiguous_rdata.data
|
||||
cdef np.double_t* cptr = <np.double_t*>contiguous_cdata.data
|
||||
|
||||
# use area of polygon to determine the rough size of the output arrays
|
||||
cdef double area = _polygon_area(contiguous_cdata, contiguous_rdata)
|
||||
|
||||
#: output coordinate arrays
|
||||
cdef np.ndarray[np.int32_t, ndim=1, mode="c"] rr, cc
|
||||
rr = np.zeros(int(area), dtype=np.int32)
|
||||
cc = np.zeros(int(area), dtype=np.int32)
|
||||
|
||||
for r in range(minr, maxr+1):
|
||||
for c in range(minc, maxc+1):
|
||||
if pnpoly(nr_verts, cptr, rptr, c, r):
|
||||
rr[i] = r
|
||||
cc[i] = c
|
||||
i += 1
|
||||
|
||||
# area >= number of points in polygon, so crop actual points
|
||||
return rr[:i], cc[:i]
|
||||
|
||||
@@ -3,4 +3,4 @@ Methods to draw on arrays.
|
||||
|
||||
"""
|
||||
|
||||
from ._draw import bresenham
|
||||
from ._draw import bresenham, polygon
|
||||
|
||||
@@ -1,7 +1,8 @@
|
||||
from numpy.testing import assert_array_equal
|
||||
import numpy as np
|
||||
|
||||
from skimage.draw import bresenham
|
||||
from skimage.draw import bresenham, polygon
|
||||
|
||||
|
||||
def test_bresenham_horizontal():
|
||||
img = np.zeros((10, 10))
|
||||
@@ -25,7 +26,7 @@ def test_bresenham_vertical():
|
||||
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
def test_reverse():
|
||||
def test_bresenham_reverse():
|
||||
img = np.zeros((10, 10))
|
||||
|
||||
rr, cc = bresenham(0, 9, 0, 0)
|
||||
@@ -36,7 +37,7 @@ def test_reverse():
|
||||
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
def test_diag():
|
||||
def test_bresenham_diag():
|
||||
img = np.zeros((5, 5))
|
||||
|
||||
rr, cc = bresenham(0, 0, 4, 4)
|
||||
@@ -47,6 +48,75 @@ def test_diag():
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
|
||||
def test_polygon_rectangle():
|
||||
img = np.zeros((10, 10), 'uint8')
|
||||
poly = np.array(((1, 1), (4, 1), (4, 4), (1, 4), (1, 1)))
|
||||
|
||||
rr, cc = polygon(poly)
|
||||
img[rr,cc] = 1
|
||||
|
||||
img_ = np.zeros((10, 10))
|
||||
img_[1:4,1:4] = 1
|
||||
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
def test_polygon_rectangle_angular():
|
||||
img = np.zeros((10, 10), 'uint8')
|
||||
poly = np.array(((0, 3), (4, 7), (7, 4), (3, 0), (0, 3)))
|
||||
|
||||
rr, cc = polygon(poly)
|
||||
img[rr,cc] = 1
|
||||
|
||||
img_ = np.array(
|
||||
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 0, 1, 1, 0, 0, 0, 0, 0, 0],
|
||||
[0, 1, 1, 1, 1, 0, 0, 0, 0, 0],
|
||||
[1, 1, 1, 1, 1, 1, 0, 0, 0, 0],
|
||||
[0, 1, 1, 1, 1, 1, 1, 0, 0, 0],
|
||||
[0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
|
||||
[0, 0, 0, 1, 1, 0, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
|
||||
)
|
||||
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
def test_polygon_parallelogram():
|
||||
img = np.zeros((10, 10), 'uint8')
|
||||
poly = np.array(((1, 1), (5, 1), (7, 6), (3, 6), (1, 1)))
|
||||
|
||||
rr, cc = polygon(poly)
|
||||
img[rr,cc] = 1
|
||||
|
||||
img_ = np.array(
|
||||
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 1, 1, 1, 0, 0, 0, 0, 0, 0],
|
||||
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0],
|
||||
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0],
|
||||
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
||||
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
|
||||
)
|
||||
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
def test_polygon_exceed():
|
||||
img = np.zeros((10, 10), 'uint8')
|
||||
poly = np.array(((1, -1), (100, -1), (100, 100), (1, 100), (1, 1)))
|
||||
|
||||
rr, cc = polygon(poly, img.shape)
|
||||
img[rr,cc] = 1
|
||||
|
||||
img_ = np.zeros((10, 10))
|
||||
img_[1:,:] = 1
|
||||
|
||||
assert_array_equal(img, img_)
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
from numpy.testing import run_module_suite
|
||||
|
||||
run_module_suite()
|
||||
|
||||
Reference in New Issue
Block a user