[FIXED] Making sequential line(cv2) from numpy array

Issue

I have a numpy array that consist n (x and y) coordinate (i declared this nparray as 'line') from an image(newimg). lets take 5 coordinates as the example

[[ 33 101]
 [170  95]
 [151 190]
 [125 223]
 [115 207]]

an then i want to make a sequential line between that coordinates (point 1 to point 2, point 2 to point 3, ...., point n-1 to point n and the point n to point 1)

I trying to make the algorithm with cv2.line like this

for a in range(5) :
   cv2.line(newimg, line[a:], line[a+1:], (255,255,255), 1)
cv2.line(newimg, line, line[1], (255,255,255), 1)

and it produce SystemError: new style getargs format but argument is not a tuple

any idea?

Solution

Problems:

There are some changes that need to be addressed:

1. To access a single value in an array use line[i]. line[i:] returns an array of points staring from index i till the end.
2. cv2.line() accepts tuples as start and end points.

Code:

# proposed line as an array
line = np.array([[ 33, 101], [170,  95], [151, 190], [125, 223], [115, 207]])

# blank image
newimg = np.zeros((300, 300, 3), np.uint8)

# iterate every point and connect a line between it and the next point
for a in range(len(line) - 1):
    newimg = cv2.line(newimg, tuple(line[a]), tuple(line[a+1]), (255,255,255), 2)
newimg = cv2.line(newimg, tuple(line[0]), tuple(line[-1]), (255,255,255), 2)

Output:

EDIT

Updated the code to connect a line between the first and last points in line

Answered By - Jeru Luke