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city_block_dist.py
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city_block_dist.py
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import scipy
import numpy
from scipy import *
def CityBlock(River_arr):
( x_len , y_len ) = River_arr.shape
#Initialize distance array
distance_arr = zeros( (x_len , y_len), dtype= "int")
infinity = x_len + y_len + 1
for i in range(0, x_len):
for j in range(0, y_len):
# Convert the gray-scale image into binary image
if River_arr[i][j] == 0:
# 0 means absence of river
distance_arr[i][j] = infinity
else:
distance_arr[i][j] = 0
# Apply distance transform
for i in range(0, x_len):
for j in range(0, y_len):
if i-1 < 0 and j-1 >=0:
distance_arr[i][j] = min(distance_arr[i][j],1 + distance_arr[i][j-1])
elif i-1 >= 0 and j-1 < 0:
distance_arr[i][j] = min(distance_arr[i][j],1 + distance_arr[i-1][j])
elif i-1 >= 0 and j-1 >= 0:
distance_arr[i][j] = min(distance_arr[i][j],1 + distance_arr[i-1][j], 1 + distance_arr[i][j-1])
for i in range(x_len-1, -1, -1):
for j in range(y_len-1, -1, -1):
if i+1 > x_len-1 and j+1 <=y_len-1:
distance_arr[i][j] = min(distance_arr[i][j],1+distance_arr[i][j+1])
elif i+1 <= x_len-1 and j+1 > y_len-1:
distance_arr[i][j] = min(distance_arr[i][j],1+distance_arr[i+1][j])
elif i+1 <= x_len-1 and j+1 <= y_len-1:
distance_arr[i][j] = min(distance_arr[i][j],1+distance_arr[i+1][j], 1+distance_arr[i][j+1])
return distance_arr