/
rolling_window_advanced.py
69 lines (60 loc) · 2.6 KB
/
rolling_window_advanced.py
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# Rolling window for 2D arrays using NumPy
import numpy as np
from PIL import Image, ImageDraw
# Rolling window for 2D array
def roll(a, # image array
b, # rolling window array
dx, # horizontal step - number of columns
dy): # vertical step - number of rows
shape = (int((a.shape[0] - b.shape[0]) / dy) + 1,) + \
(int((a.shape[1] - b.shape[1]) / dx) + 1,) + b.shape
strides = (a.strides[0] * dy, a.strides[1] * dx,) + a.strides
return np.lib.stride_tricks.as_strided(a, shape=shape, strides=strides)
a = np.array([[0, 1, 2, 3, 4, 5],
[7, 8, 7, 8, 10, 11],
[13, 14, 13, 14, 7, 8],
[19, 20, 19, 20, 13, 14],
[24, 25, 26, 27, 19, 20],
[30, 31, 32, 33, 34, 35]], dtype=np.int)
c = np.arange(36, dtype=np.float).reshape(6,6)
# Array present is occurred in array a two times on [1,1] and [2,4].
present = np.array([[7,8],[13,14],[19,20]], dtype=np.int)
absent = np.array([[7,8],[42,14],[19,20]], dtype=np.int)
dx, dy = 1, 1
found = np.all(np.all(roll(a, present, dx, dy) == present, axis=2), axis=2)
print(np.transpose(found.nonzero()) * [dy, dx])
dx, dy = 2, 1
found = np.all(np.all(roll(a, present, dx, dy) == present, axis=2), axis=2)
print(np.transpose(found.nonzero()) * [dy, dx])
dx, dy = 1, 1
found = np.all(np.all(roll(c, present, dx, dy) == present, axis=2), axis=2)
print(np.transpose(found.nonzero()) * [dy, dx])
dx, dy = 1, 1
found = np.all(np.all(roll(a, absent, dx, dy) == absent, axis=2), axis=2)
print(np.transpose(found.nonzero()) * [dy, dx])
x = np.array([[1,2],[3,4],[5,6],[7,8],[9,10],[3,4],[5,6],[7,8],[11,12]])
y = np.array([[3,4],[5,6],[7,8]])
dx, dy = 1, 1
found = np.all(np.all(roll(x, y, dx, dy) == y, axis=2), axis=2)
print(found.nonzero()[0] * dy)
#print(roll(a, present, 2, 1)) # debug
width = 10
height = 10
polygon = [(1,2), (9,1), (5,8)]
img = Image.new('L', (width, height), 0) # using gray 'L' array for debug purposes
ImageDraw.Draw(img).polygon(polygon, fill=1)
mask = np.array(img)
print(mask, '\n')
ImageDraw.Draw(img).polygon(polygon, outline=1, fill=1)
mask = np.array(img)
print(mask, '\n')
ImageDraw.Draw(img).polygon(polygon, outline=0, fill=1)
mask = np.array(img)
print(mask, '\n')
img = Image.new('1', (width, height), False) # better to use bitwise '1' array
ImageDraw.Draw(img).polygon(polygon, outline=True, fill=True)
mask = np.array(img, dtype=np.bool)
rolling_window = np.full((2, 2), True, dtype=np.bool)
dx, dy = 1, 1
found = np.all(np.all(roll(mask, rolling_window, dx, dy) == rolling_window, axis=2), axis=2)
print(np.transpose(found.nonzero()) * [dy, dx])