Python CalcEMD2 gives wrong result (Bug #1763)

The following Python script gives result 0, but 1.0 is expected.

However, if you add lower_bound=float('inf') to the calling of CalcEMD2, you will be able to get correct result.

This is probably because lower_bound is set to 0 instead of a NULL pointer in the Python wrapper, which causes the actual cvCalcEMD2 implementation skips EMD calculation, since the lower bound in the below test case is just 0.

 1import cv
 2
 3def toSig(b):
 4    m = cv.CreateMat(len(b), 2, cv.CV_32FC1)
 5    for i, x in enumerate(b):
 6        m[i, 0] = 1
 7        m[i, 1] = x
 8    return m
 9
10def test():
11    b1 = [0,0,0,0]
12    b2 = [-1, 1, 1, -1]
13
14    s1 = toSig(b1)
15    s2 = toSig(b2)
16    print cv.CalcEMD2(s1, s2, cv.CV_DIST_L1) 
17    #To get correct result:
18    #print cv.CalcEMD2(s1, s2, cv.CV_DIST_L1, lower_bound=float('inf'))
19
20test()