Ignite metrics (recall, precision, etc) - thresholded_output_transform

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I’m working on a binary task and I’m figuring out Recall, Precision, etc, as implemented by Ignite. As per documentation:

“In binary and multilabel cases, the elements of y and y_pred should have 0 or 1 values. Thresholding of predictions can be done as below:”

def thresholded_output_transform(output):
            y_pred, y = output
            y_pred = torch.round(y_pred)
            return y_pred, y

Am I correct to assume that output is what is returned by the model?
I’m using BCEWithLogitsLoss, so I have to pass logits through a sigmoid function. I have to use a sigmoid here as well, right?

def thresholded_output_transform(output):
            y_pred, y = output 
            y_pred = torch.sigmoid(y_pred)
            y_pred = torch.clamp(y_pred, 0., 1.)
            y_pred = torch.round(y_pred)
            return y_pred, y
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Output is what is returned by evaluator’s process_function : ignite.metrics — PyTorch-Ignite v0.4.13 Documentation

I’m using BCEWithLogitsLoss, so I have to pass logits through a sigmoid function. I have to use a sigmoid here as well, right?

Well, it depends on your choice how to define whether logit’s value is sufficient to be interpreted as 1.
Yes, it is more convenient to pass to “probabilties” using sigmoid and then apply a thresholding (0.5) as you put to your version of thresholded_output_transform.

Here is another way to apply the thresholding:

t = 0.55

def thresholded_output_transform(output):
    y_pred, y = output 
    y_pred = torch.sigmoid(y_pred)
    y_pred = (y_pred > t).float()
    return y_pred, y
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3

@vfdev-5 nice! Thanks!

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