Using awk to get the maximum of a value in two different ranges

Shell Programming and Scripting
1

Dear Unix gurus,

I have sample data organised like this and containing 6 columns (with headers):

label c2 c3 c4 c5 c6

where c2 to c6 are numeric values in columns c2 to 6.

I am trying to create a simple output in a new file containing 3 columns:

label max(c2 c3) max(c4 c5 c6)

where max is the maximum numerical value of columns 2-3 and 4-6.

I have been trying to do it with awk but somehow don't manage to get the syntax right...

Many thanks for your time and help!

KS

2 
awk '
{
($(NF-1) > $(NF)) ? _ : ($(NF-1)=$(NF)) ; NF--;
($(NF-1) > $(NF)) ? _ : ($(NF-1)=$(NF)) ; NF--;
max2=$NF ; NF--;
($(NF-1) > $(NF)) ? _ : ($(NF-1)=$(NF)) ; NF--;
($(NF-1) > $(NF)) ? _ : ($(NF-1)=$(NF)) ; NF--;
$0=$0 OFS max2;
print $0;
}
' OFS="\t" infile
3

Thank you very much for your fast reply!

I tried and it seems that it doesn't work on my data: I just get calculations at the end of the output that don't really seem to make sense.

Could you please detail the code so I can investigate? Thank you very much

---------- Post updated at 03:07 PM ---------- Previous update was at 02:57 PM ----------

I thought I would give a more concrete example of my problem.
My input file is as follows:

label1	0	0	0	0	0	1
label2	0	0	0	0	0	1
label3	0.2	0.2	0.9	0	0	0
label4	0	0	0.8	0.1	0	0
label5	0.1	0.1	0.1	0.15	0.1	0.1
label6	0.1	0.15	0.1	0.1	0.1	0.1

with column 1 being a header of the row, and columns 2 to 7 being numerical values.

The output I would like is:

label1	0	1
label2	0	1
label3	0.9	0
label4	0.8	0.1
label5	0.1	0.15
label6	0.15	0.1

with:
column 1 = column 1 from the input
column 2 = maximum value of columns 2 to 4 from the input
column 3 = maximum value of columns 5 to 7 from the input

Many thanks!!

4

Thanks to the example things are clear now.

#!/bin/sh
awk '
  function maxcol(startcol,endcol){
    _maxcol=$startcol
    while (++startcol<=endcol) {
      if ($startcol>_maxcol) _maxcol=$startcol
    }
    return _maxcol
  }
  { print $1, maxcol(2,4), maxcol(5,7) }
' infile
1 Like
5

Many thanks, it works perfectly!!!