百分制计算 [英] Percentile calculation

问题描述

我想模仿 Excel的相当于百分位数函数C＃（或者在一些伪code）。我该怎么办呢？该函数应该用两个参数，其中第一个是值的列表，第二是为了什么百分函数应该计算。

I want to mimic the Excel equivalent PERCENTILE function in C# (or in some pseudo code). How can I do that? The function should take two arguments where the first is a list of values and the second is for what percentile the function should calculate for.

坦克！

编辑：我很抱歉，如果我的问题碰到像我以前没有尝试过我自己。我就是不明白是怎么Excel函数工作（是的，我尝试维基百科和钨第一），我想我会更好地理解它，如果有人$ P $在code psented它。 @ codeInChaos了，似乎是我后一个答案。

I'm sorry if my question came across like I had not tried it my self. I just couldn't understand how the excel function worked (yes, I tried wikipedia and wolfram first) and I thought I would understand it better if someone presented it in code. @CodeInChaos gave an answer that seem to be what I'm after.

推荐答案

我觉得维基百科页面有公式，你需要写自己的功能...
我想这样的：

I think Wikipedia page has formulas you need to write your own function...
I tried this:

public double Percentile(double[] sequence, double excelPercentile)
{
    Array.Sort(sequence);
    int N = sequence.Length;
    double n = (N - 1) * excelPercentile + 1;
    // Another method: double n = (N + 1) * excelPercentile;
    if (n == 1d) return sequence[0];
    else if (n == N) return sequence[N - 1];
    else
    {
         int k = (int)n;
         double d = n - k;
         return sequence[k - 1] + d * (sequence[k] - sequence[k - 1]);
    }
}

codeInChaos评论后编辑：
Excel使用0和1之间（所以我改变了我的code维基百科的公式来实现这一点），另一个方法的百分位值calulate N（所以我改变了评论的）。

EDITED after CodeInChaos comment:
Excel uses a percentile value between 0 and 1 (so I changed my code to implement this with Wikipedia formulas) and the other method to calulate n (so I changed the commented one).

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