database - 如何使用awk查找列中的最大值

Question

我有一个文件，其中包含由空行分隔的两组数据:

a     3  
b     2  
c     1 

e     5   
d     8  
f     1  

有没有办法找到每组中第二列的最大值并用 awk 打印相应的行？结果应该是:

b 3  
d 8  

谢谢。

Answer 1

您能否尝试按照您在 GNU awk 中显示的示例进行编写和测试。

awk '
!NF{
  if(max!=""){ print arr[max],max }
           max=""
  }
{
    max=( (max<$2) || (max=="") ? $2 : max )
    arr[$2]=$1
}
END{
  if(max!=""){ print arr[max],max }
}
'  Input_file

说明:为上述内容添加详细说明。

awk '                            ##Starting awk program from here.
!NF{                             ##if NF is NULL then do following.
  if(max!=""){ print arr[max],max }  ##Checking if max is SET then print arr[max] and max.
  max=""                         ##Nullifying max here.
  }
{
  max=( (max<$2) || (max=="") ? $2 : max )      ##Checking condition if max is greater than 2nd field then keep it as max or change max value as 2nd field.
  arr[$2]=$1                     ##Creating arr with 2nd field index and 1st field as value.
}
END{                             ##Starting END block of this program from here.
  if(max!=""){ print arr[max],max }  ##Checking if max is SET then print arr[max] and max.
}
' Input_file                     ##mentioning Input_file name here.