Class ScalarStats

tensorpack/callbacks/inference.py:91–132

Statistics of some scalar tensor. The value will be averaged over all given datapoints. Note that the average of accuracy over all batches is not necessarily the accuracy of the whole dataset. See :class:`ClassificationError` for details.

class ScalarStats(Inferencer):
    """
    Statistics of some scalar tensor.
    The value will be averaged over all given datapoints.

    Note that the average of accuracy over all batches is not necessarily the
    accuracy of the whole dataset. See :class:`ClassificationError` for details.
    """

    def __init__(self, names, prefix='validation'):
        """
        Args:
            names(list or str): list of names or just one name. The
                corresponding tensors have to be scalar.
            prefix(str): a prefix for logging
        """
        if not isinstance(names, list):
            self.names = [names]
        else:
            self.names = names
        self.prefix = prefix

    def _before_inference(self):
        self.stats = []

    def _get_fetches(self):
        return self.names

    def _on_fetches(self, output):
        self.stats.append(output)

    def _after_inference(self):
        if len(self.stats):
            self.stats = np.mean(self.stats, axis=0)
            assert len(self.stats) == len(self.names)

        ret = {}
        for stat, name in zip(self.stats, self.names):
            opname, _ = get_op_tensor_name(name)
            name = '{}_{}'.format(self.prefix, opname) if self.prefix else opname
            ret[name] = stat
        return ret


class ClassificationError(Inferencer):