awk列的中位数 [英] median of column with awk

问题描述

如何使用AWK计算一列数值数据的中位数?

How can I use AWK to compute the median of a column of numerical data?

我可以想到一个简单的算法，但是我似乎无法对其进行编程:

I can think of a simple algorithm but I can't seem to program it:

到目前为止，我有:

sort | awk 'END{print NR}' 

这给了我列中元素的数量.我想用它来打印特定的行(NR/2).如果NR/2不是整数，则四舍五入到最接近的整数，即中位数，否则取(NR/2)+1和(NR/2)-1的平均值.

And this gives me the number of elements in the column. I'd like to use this to print a certain row (NR/2). If NR/2 is not an integer, then I round up to the nearest integer and that is the median, otherwise I take the average of (NR/2)+1 and (NR/2)-1.

推荐答案

此awk程序假定一列数字排序的数据:

This awk program assumes one column of numerically sorted data:

#/usr/bin/env awk
{
    count[NR] = $1;
}
END {
    if (NR % 2) {
        print count[(NR + 1) / 2];
    } else {
        print (count[(NR / 2)] + count[(NR / 2) + 1]) / 2.0;
    }
}

样品用量:

sort -n data_file | awk -f median.awk

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