用awk找一列平均 [英] Use awk to find average of a column

问题描述

我试图找到数据的第二列使用 AWK 一类的平均水平。这是我目前的code，与我的导师提供的框架：

 ＃！/ bin中/ AWK###此脚本当前打印处理的行的总数。
###你必须编辑这个脚本打印的第2列的平均
代替行数###。＃code的此块是文件中的每一行执行
{
X =总和
读名
        awk的'BEGIN {总和+ = $ 2}'
        ＃脚本不应该为每一行打印出来的值
}
＃结束块的最后一行被读取后处理
结束 {
        ＃NR是一个变量等于行数的文件中
        打印平均之和/ NR
        ＃更改为打印而不是平均的行只是数
}
 

和我收到一个错误，指出：

  AWK：avg.awk：11：awk的'BEGIN {总和+ = $ 2}'$名
AWK：avg.awk：11：恩$ P $ ^ pssion字符无效'''
 

我想我接近，但我真的不知道该去哪里从这里走。在code应该不会像我们所看到的在课堂上一直还算基本都极其复杂。请让我知道。

解决方案

 的awk'{总和+ = $ 2; ñ++} END {如果（N大于0）打印总和/ N; }
 

添加号码 $ 2 在总和（第二列）（变量自动初始化为零通过 AWK ），并增加行（其数量也可以通过内置变量NR处理）。最后，如​​果有值读取的至少一个，输出平均

 的awk'{总和+ = $ 2} END {如果（NR大于0）打印总和/ NR}'
 

如果您要使用的家当符号，你可以写：

 ＃！/ bin中/ AWK{总和+ = $ 2}
END {如果（NR大于0）打印总和/ NR}
 

您也可以控制平均与的printf（）和一个合适的格式（％13.6e \\ N，例如）。

您也可以概括code均价第N列（与 N = 2 此示例中）使用：

 的awk -v N = 2'{总和+ = $ N} END {如果（NR大于0）打印总和/ NR}'
 

I'm attempting to find the average of the second column of data using awk for a class. This is my current code, with the framework my instructor provided:

#!/bin/awk

### This script currently prints the total number of rows processed.
### You must edit this script to print the average of the 2nd column
### instead of the number of rows.

# This block of code is executed for each line in the file
{
x=sum
read name
        awk 'BEGIN{sum+=$2}'
        # The script should NOT print out a value for each line
}
# The END block is processed after the last line is read
END {
        # NR is a variable equal to the number of rows in the file
        print "Average: " sum/ NR
        # Change this to print the Average instead of just the number of rows
}

and I'm getting an error that says:

awk: avg.awk:11:        awk 'BEGIN{sum+=$2}' $name
awk: avg.awk:11:            ^ invalid char ''' in expression

I think I'm close but I really have no idea where to go from here. The code shouldn't be incredibly complex as everything we've seen in class has been fairly basic. Please let me know.

解决方案

awk '{ sum += $2; n++ } END { if (n > 0) print sum / n; }'

Add the numbers in $2 (second column) in sum (variables are auto-initialized to zero by awk) and increment the number of rows (which could also be handled via built-in variable NR). At the end, if there was at least one value read, print the average.

awk '{ sum += $2 } END { if (NR > 0) print sum / NR }'

If you want to use the shebang notation, you could write:

#!/bin/awk

{ sum += $2 }
END { if (NR > 0) print sum / NR }

You can also control the format of the average with printf() and a suitable format ("%13.6e\n", for example).

You can also generalize the code to average the Nth column (with N=2 in this sample) using:

awk -v N=2 '{ sum += $N } END { if (NR > 0) print sum / NR }'

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