Smoothed loss callback

running_loss.py

class RollingLoss(Callback):

    def __init__(self, smooth=0.98):
        self.smooth = smooth

    def batch_ended(self, phase, **kwargs):
        prev = phase.rolling_loss
        a = self.smooth
        avg_loss = a * prev + (1 - a) * phase.batch_loss
        debias_loss = avg_loss / (1 - a ** phase.batch_index)
        phase.rolling_loss = avg_loss
        phase.update(debias_loss)

    def epoch_ended(self, phases, **kwargs):
        for phase in phases:
            phase.update_metric('loss', phase.last_loss)