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scikit-image/skimage/transform/tests/test_hough_transform.py
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Python

import numpy as np
from numpy.testing import *
import skimage.transform as tf
import skimage.transform.hough_transform as ht
from skimage.transform import probabilistic_hough
def append_desc(func, description):
"""Append the test function ``func`` and append
``description`` to its name.
"""
func.description = func.__module__ + '.' + func.__name__ + description
return func
from skimage.transform import *
def test_hough():
# Generate a test image
img = np.zeros((100, 100), dtype=int)
for i in range(25, 75):
img[100 - i, i] = 1
out, angles, d = tf.hough(img)
y, x = np.where(out == out.max())
dist = d[y[0]]
theta = angles[x[0]]
assert_equal(dist > 70, dist < 72)
assert_equal(theta > 0.78, theta < 0.79)
def test_hough_angles():
img = np.zeros((10, 10))
img[0, 0] = 1
out, angles, d = tf.hough(img, np.linspace(0, 360, 10))
assert_equal(len(angles), 10)
def test_py_hough():
ht._hough, fast_hough = ht._py_hough, ht._hough
yield append_desc(test_hough, '_python')
yield append_desc(test_hough_angles, '_python')
tf._hough = fast_hough
def test_probabilistic_hough():
# Generate a test image
img = np.zeros((100, 100), dtype=int)
for i in range(25, 75):
img[100 - i, i] = 100
img[i, i] = 100
# decrease default theta sampling because similar orientations may confuse
# as mentioned in article of Galambos et al
theta = np.linspace(0, np.pi, 45)
lines = probabilistic_hough(img, theta=theta, threshold=10, line_length=10,
line_gap=1)
# sort the lines according to the x-axis
sorted_lines = []
for line in lines:
line = list(line)
line.sort(key=lambda x: x[0])
sorted_lines.append(line)
assert([(25, 75), (74, 26)] in sorted_lines)
assert([(25, 25), (74, 74)] in sorted_lines)
if __name__ == "__main__":
run_module_suite()