Average multiple CSV files

average.awk

#!/bin awk -f

BEGIN {
  FS=","
  rows[""]=0
  rowsc[""]=0
  labels[""]=0
}
{
  if (NR == 1) { header=$0; cols=NF; }
  else if ($0 != header) {
    labels[$1]++
    for (i=2; i<=NF; i++) {
      rows[$1 " " i] += $i
      rowsc[$1 " " i]++
    }
  }
}
END {
  print header
  for (label in labels) {
    if (label == "") continue
    line=label
    for (i=2; i<=cols; i++) {
      if (rowsc[label " " i]) {
        avg=rows[label " " i]/rowsc[label " " i]
        line=sprintf("%s,%8.4f", line, avg)
      }
    }
    print line
  }
}