# --------------------------------------------------------
# X-Decoder -- Generalized Decoding for Pixel, Image, and Language
# Copyright (c) 2022 Microsoft
# Licensed under The MIT License [see LICENSE for details]
# Written by Xueyan Zou (xueyan@cs.wisc.edu)
# --------------------------------------------------------
import math



class AverageMeter(object):
    """Computes and stores the average and current value."""
    def __init__(self):
        self.reset()

    def reset(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

    def update(self, val, n=1, decay=0):
        self.val = val
        if decay:
            alpha = math.exp(-n / decay)  # exponential decay over 100 updates
            self.sum = alpha * self.sum + (1 - alpha) * val * n
            self.count = alpha * self.count + (1 - alpha) * n
        else:
            self.sum += val * n
            self.count += n
        self.avg = self.sum / self.count