to find min and max value for each column!

Shell Programming and Scripting
1

Hello Experts,
I have got a txt files which has multiple columns, I want to get the max, min and diff (max-min) for each column in the same txt file. Example:

cat file.txt

a 1 4
b 2 5
c 3 6

I want ouput like:
cat file.txt

a 1 4
b 2 5
c 3 6
Max 3 6
Min 1 4
Diff 2 2

awk 'min=="" || $2 < min {min=$2} END{print min}' file.txt

this awk command can find min from 2 column, but i have to change the column number, is there a one liner which can give me desired output in the same text file.
Thanks in advance.

2

You can do a loop from 2 to NF and do that minimum bit on each column, storing in an array, then print the arrays in loops too...

awk '{
        for(N=2; N<=NF; N++) { 
                if((!MIN[N])||(MIN[N]>$N)) MIN[N]=$N
                if((!MAX[N])||(MAX[N]<$N)) MAX[N]=$N }
        END {
                printf("MIN");
                for(N=2; length(MIN[N]); N++)
                        printf("\t%s", MIN[N]);
                printf("\n");
                printf("MAX");
                for(N=2; length(MIN[N]); N++)
                        printf("\t%s", MAX[N]);
                printf("\n");
                printf("DIFF");
                for(N=2; length(MIN[N]); N++)
                        printf("\t%s", MAX[N]-MIN[N]);
                printf("\n");
        }' filename
3

Loop around the number of fields and create 2 arrays.
e.g.

awk '
{
   for (i=2;i<=NF;i++) {
      if (i in min) {
         if ($i < min) {
            min=$i;
         }
      } else {
         min=$i;
      }
      if (i in max) {
        ...etc...
   }
}1
END {
   printf ("Min: ");
   for (i in min) {
      printf ("%d ", min)
   }
   printf ("\n");
  etc...
}
4

If I want to start the loop from second row (since the first row is the header) and second column what changes I should make to the above logic?

5 
NR>1 {
    for stuff