    def _collate_frames(self, frames):
        """Convert a list of 2d frames into a padded 3d tensor
        Args:
            frames (list): list of 2d frames of size L[i]*f_dim. Where L[i] is
                length of i-th frame and f_dim is static dimension of features
        Returns:
            3d tensor of size len(frames)*len_max*f_dim where len_max is max of L[i]
        """
        len_max = max(frame.size(0) for frame in frames)
        f_dim = frames[0].size(1)
        res = frames[0].new(len(frames), len_max, f_dim).fill_(0.0)

        for i, v in enumerate(frames):
            res[i, : v.size(0)] = v

        return res
Convert a list of 2d frames into a padded 3d tensor
Args:
frames (list): list of 2d frames of size L[i]*f_dim. Where L[i] is
length of i-th frame and f_dim is static dimension of features
Returns:
3d tensor of size len(frames)*len_max*f_dim where len_max is max of L[i]
examples/speech_recognition/data/collaters.py