def __call__(self, pred, true):
    fgr_mask = (true > 0)
    return ((pred[fgr_mask] - true[fgr_mask]).abs_().mean() * 1000.0)
def __call__(self, pred, true):
    fgr_mask = (true > 0)
    return ((pred[fgr_mask] - true[fgr_mask]).abs_().mean() * 1000.0)