使用awk或shell脚本或python将文件中单个列的所有组合创建为两列

Question

I have a file which contains airport code like below

ATQ 
HYD 
BLR
GOI 
AMD
CCJ
TRV

from the same file i have to create source destination mapping like below in gawk.

 src dest
 ATQ HYD
 ATQ BLR
 ATQ GOI
 ATQ AMD
 ATQ CCJ
 ATQ TRV
 HYD ATQ
 HYD BLR
 HYD AMD
 ....
 ...

can anyone help me here,thanks in advance

Answer 1

A simple awk script could do this. Just store all the elements of the line in array and run a loop for each element for every other element without repetitions which don't make sense.

$ awk 'BEGIN {printf("%s\t%s\n" ,"src", "dest")}
  {
      line[++c] = $1
  }
  END {
      for ( i = 1; i <= c; i++ )
      {
          for ( j = 1; j <= c; j++ )
          {
              if (line[i] != line[j]) { printf("%s\t%s\n",line[i],line[j]) }
          }
       }
  }
' file

will output,

src     dest
ATQ     HYD
ATQ     BLR
ATQ     GOI
ATQ     AMD
ATQ     CCJ
ATQ     TRV
HYD     ATQ
HYD     BLR
HYD     GOI
HYD     AMD
HYD     CCJ
HYD     TRV
BLR     ATQ
BLR     HYD
BLR     GOI
BLR     AMD
BLR     CCJ
BLR     TRV
GOI     ATQ
GOI     HYD
GOI     BLR
GOI     AMD
GOI     CCJ
GOI     TRV
AMD     ATQ
AMD     HYD
AMD     BLR
AMD     GOI
AMD     CCJ
AMD     TRV
CCJ     ATQ
CCJ     HYD
CCJ     BLR
CCJ     GOI
CCJ     AMD
CCJ     TRV
TRV     ATQ
TRV     HYD
TRV     BLR
TRV     GOI
TRV     AMD
TRV     CCJ

Answer 2

One liner:

 echo "src dest"; cat /tmp/air | while read s; do for d in `cat /tmp/air`; do if [ $s != $d ]; then echo $s $d; fi; done; done

Will output:

src dest
ATQ HYD
ATQ BLR
ATQ GOI
ATQ AMD
ATQ CCJ
ATQ TRV
HYD ATQ
HYD BLR
HYD GOI
HYD AMD
HYD CCJ
HYD TRV
BLR ATQ
BLR HYD
BLR GOI
BLR AMD
BLR CCJ
BLR TRV
GOI ATQ
...

Answer 3

Version in bash assuming your airport list is in a.txt file:

echo "src dest";
for src in `cat a.txt`; do
    for dest in `cat a.txt`; do
        if [ $src != $dest ]; then
            echo "$src $dest";
        fi
    done;
done