Indexing flaw, changing color of Vertices-CodePudding

Keep making same mistake.

Horizontal lines is always result. Trying to display random points.


import cv2 as cv, numpy as np, random
blank = np.ones((300,300), np.uint8) * 255

X, Y = [], []

for i in np.arange(1,300,1):
    X.append(random.randrange(1,300))
for i in np.arange(1,300,1):
    Y.append(random.randrange(1,300))

XY = np.column_stack((np.asarray(X),np.asarray(Y)))

# change values of Vertex index to black. 
blank[XY] = 1

cv.imshow('', blank)
cv.waitKey(0)
cv.destroyAllWindows()

Random array of pixels is intended.

CodePudding user response：

Everything is okay in your code, just require some change which is that we have to pass X, Y instead of XY.

blank[X, Y] = 1

So basically index operater [] requires a tuple so we can create our own using XY.

# tuple(XY.transpose())
blank[tuple(XY.transpose())] = 1

import cv2 as cv, numpy as np, random
blank = np.ones((300,300), np.uint8) * 255

X, Y = [], []

for i in np.arange(1,300,1):
    X.append(random.randrange(1,300))
for i in np.arange(1,300,1):
    Y.append(random.randrange(1,300))

# XY = np.column_stack((np.asarray(X),np.asarray(Y)))

# change values of Vertex index to black. 
blank[X, Y] = 1

cv.imshow('', blank)
cv.waitKey(0)
cv.destroyAllWindows()

OUTPUT: