Error in prediction classes array for inference method in evaluator.py

[MurielleMardenli200]

Issue with evaluation:

I am using detectron in order to make predictions for 1 class only (with a value of 0). When I try to use the inference_on_dataset() method, I am getting the following error:

[11/22 12:05:36 d2.evaluation.coco_evaluation]: Preparing results for COCO format ...
Validation run stopped due to:A prediction has class=62, but the dataset only has 1 classes and predicted class id should be in [0, 0].

When I try to look at outputs variable containing the pred_classes array in the inference_on_dataset() method (line 165), I see that it contains an array with some 0 values (correct class prediction), but some random values ranging from 0-100 as well, with the first number of the array being 62 (the number in the error). The number of zeros was shortened for readability:

tensor([ 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0,  0, 62,  0, 60,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0, 59,  0,  0,  0,  0,  0,  0,  0,  0,  8,  0,
         0,  0,  0, 60,  0, 53,  0,  0,  0, 25,  0, 60, 73, 58, 63,  0,  4,  0,
        60, 69,  0,  0,  0,  6,  0, 37,  0,  0,  0,  0, 60, 74, 55, 60,  0,  0,
        71,  0, 13,  0,  0, 57, 56,  2, 60, 73, 72, 13,  0, 60, 72, 39, 32, 37,
        60, 37, 59, 13,  5, 50, 53, 73, 60, 60, 59])

The pred_classes array has the same size as the pred_boxes array, which shows it does contain the right predictions. When I replace the pred_classes array with an array of the same size filled with zeros (expected behavior), the method does not throw an error anymore.

How can I fix this issue?

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