您好 假设我有一组数字我想快速计算均匀性的一些措施。 我知道这个变化是最明显的答案，但我怕天真的算法的复杂度太高 任何人有什么建议？

Hello Assume I have the set of numbers I want a quick to calculate some measure of uniformity. I know the variance is the most obvious answer but i am afraid the complexity of naive algorithm is too high Anyone have any suggestions?

推荐答案

直观的算法来计算方差，通常患有一种或两种以下内容：

"Intuitive" algorithms for calculating variance usually suffer one or both of the following:

有一个很好的算法，只有一个回路，数值稳定是由于 D.克努特（一如既往）。

A good algorithm, with only one loop and numerically stable is due to D. Knuth (as always).

维基百科：

n = 0
mean = 0
M2 = 0
 def calculate_online_variance(x):
    n = n + 1
    delta = x - mean
    mean = mean + delta/n
    M2 = M2 + delta*(x - mean)  # This expression uses the new value of mean

    variance_n = M2/n
    variance = M2/(n - 1) #note on the first pass with n=1 this will fail (should return Inf)
    return variance

您应该调用calculate_online_variance（x）的每一个点，并返回到目前为止计算出的差异。

You should invoke calculate_online_variance(x) for each point, and it returns the variance calculated so far.