Convert column to matrix format using awk

Question

I have a gridded data file in column format as:

ifile.txt
x     y     value
20.5  20.5  -4.1
21.5  20.5  -6.2
22.5  20.5   0.0
20.5  21.5   1.2
21.5  21.5   4.3
         


        

Answer 1

Adjusted my old GNU awk solution for your current input data:

matrixize.awk script:

#!/bin/awk -f
BEGIN { PROCINFO["sorted_in"]="@ind_num_asc"; OFS="\t" }
NR==1{ next }
{
    b[$1];               # accumulating unique indices
    ($1 != $2)? a[$1][$2] = $3 : a[$2][$1] = $3; # set `diagonal` relation between different indices 
}
END {
    h = "";
    for (i in b) {
        h = h OFS i     # form header columns
    } 
    print h;            # print header column values
    for (i in b) { 
        row = i;        # index column
        # iterating through the row values (for each intersection point)
        for (j in a[i]) {
            row = row OFS a[i][j]
        } 
        print row  
    }
}

---

Usage:

awk -f matrixize.awk yourfile

The output:

    20.5    21.5    22.5
20.5  -4.1  1.2   7.0
21.5  -6.2  4.3   10.4
22.5  0.0   6.0   16.7