Question

假设我们有一个像marks.log这样的日志文件，内容如下所示：

Fname   Lname   Net Algo    
Jack    Miller  15  20  
John    Compton 12  20  
Susan   Wilson  13  19

我想添加一个新列，其中包含每个人的平均值，以及一个包含每个课程平均值的新行。结果必须如下所示：

Fname   Lname   Net  Algo  Avg
Jack    Miller  15   20    17.5
John    Compton 12   20    16
Susan   Wilson  13   19    16
Average         13.3 19.6  -

Answer 1

如果您的数据位于datafile.txt，则awk的语法可能类似于：

awk '
  {
  # If it is the first row
  if (NR==1)
  print $0, "Avg";
  else
  # Print all fields, then the average of fields 3 & 4
  print $0,($3+$4)/2;
  # Get the total for field 3 and field 4
  t3+=$3; t4+=$4
  }
  # Once that is done...
  END {
  # Print the final line
  printf "Overall Average %.1f %.1f -\n",
  # The average of field 3 (NR is the Number of Records)
  t3/(NR-1),
  # The average of field 4 (NR is the Number of Records)
  t4/(NR-1);
  }' datafile.txt

这是带注释的长版本。单线看起来像：

awk '{if (NR==1) print $0, "Avg"; else print $0,($3+$4)/2; t3+=$3; t4+=$4}END{printf "Overall Average %.1f %.1f -\n",t3/(NR-1),t4/(NR-1);}' datafile.txt

这应匹配所需的输出。

Answer 2

怎么样：

gawk '{if (NR==1) { print $0, "Avg"; tn = 0; ta = 0; c = 0; } else { print $0,($3+$4)/2; tn = tn + $3; ta = ta + $4; c = c + 1; } } END {print "Average", tn/c, ta/c, c; }' <filename>

Answer 3

不使用awk的冗长解决方案可能是：

#!/bin/bash
A=0
B=0

process(){
  A=$(( $A + $3 ))
  B=$(( $B + $4 ))
}
get_mean(){
  val=$( echo "($3 + $4)/2" | bc -l)
  printf "%.1f" $val
}

line_id=0
while read line
do
  line_id=$(( $line_id + 1 ))
  if [ $line_id -le 1 ]; then
    echo "Fname   Lname   Net  Algo  Avg"
    continue
  fi

  process $line
  mean=$(get_mean $line)

  echo $line $mean
done
A=$(echo "$A/($line_id-1)" | bc -l)
B=$(echo "$B/($line_id-1)" | bc -l)
printf "Average\t\t%.1f %.1f -" $A $B

然后可以将此脚本调用为./test.sh < input。

Bash命令用于计算每行和每列的平均值

3 个答案: