Python - array subset using another array, getting IndexError

Question

I'm having troubles with the simple task of slicing an array based on another array's values.

I have the array scores, with shape:

scores.shape = (1, 100, 1)

providing confidence scores for 100 detections in every image in a batch (but I'm using a single image, so I only have one element in the batch). So, for the first and only image, I have values for 100 detection::

scores[0] -> [score00, ..., score99]

Then, I have another similar array, bboxes...for each image in the batch (again, using only one image), and for all the 100 detections in each image, it contains 4 values. So the shape is:

bboxes.shape = (1, 100, 4)

For the only image, I have 100 quadruples of values

bboxes[0] -> [ [x_min, y_min, x_max, y_max], ..., [x_min, y_min, x_max, y_max] ]

and, out of these 100 quadruples, I need to extract only those corresponding to the elements in scores whose value is higher than a certain threshold (0.5). So, say that only the first 2 scores are higher than the threshold, I would want only the first 2 quadruples.

I'm trying something like:

print(bboxes[0][scores[0]>0.5])

but I'm getting the error:

IndexError: boolean index did not match indexed array along dimension 1; dimension is 4 but corresponding boolean dimension is 1

What am I doing wrong?

scores[0]>0.5 is a boolean...

Ramesh Reddy
– Ramesh Reddy

2020-02-03 13:32:13 +00:00
Commented Feb 3, 2020 at 13:32 — Ramesh Reddy
– Ramesh Reddy, Commented Feb 3, 2020 at 13:32

kalzso · Accepted Answer · 2020-02-03 13:44:01Z

1

Try this:

for score, box in zip(scores[0], bboxes[0]):
    if score > 0.5:
        print(box)

answered Feb 3, 2020 at 13:44

kalzso

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1 Comment

Carlo Over a year ago

Yes, it works, thank you very much! Honestly, I didn't try this way because I was trying to figure out to get the values without using for loops, but I didn't manage to do it yet.

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