CODEWITHSUNDEEP
pythonarraysopencvnumpyelement
user3377126
user3377126

Reputation: 2171

Getting element from a certain numpy array returned from OpenCV?

I am trying to get information (coordinates) that is within a numpy array and I am having a difficult time extracting information from it.

The numpy array was returned by an openCV method, cv2.calcOpticalFlowPyrLK, which produced coordinates of each point in a numpy array.

This is the output for a single point:

[[[ 292.61154175  264.74569702]]]

Small sample of the code:

p1, st, err = cv2.calcOpticalFlowPyrLK(old_gray, frame_gray, p0, None, **lk_params)

good_new = p1[st==1]
good_old = p0[st==1]

How do I extract those numbers individually from that type of numpy array?

Upvotes: 1

Views: 812

Answers (1)

dlask
dlask

Reputation: 8982

import numpy

# create such a nested array
d = numpy.array([[[1, 2]]])

# test that we can access individual elements
assert d[0, 0, 0] == 1
assert d[0, 0, 1] == 2

UPDATE:

Please note that the above indexing works only with numpy arrays. The standard Python nested lists like e = [[[1, 2]]] must be indexed in the standard Python way: e[0][0][0].

Upvotes: 2

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