awk: keep records with the highest value, comparin

Question

I'm trying to write an awk script that keeps the records with a highest value in a given field, but only comparing records that share two other fields.

I'd better give an example -- this is the input.txt:

X A 10.00
X A 1.50
X B 0.01
X B 4.00
Y C 1.00
Y C 2.43

I want to compare all the records sharing the same value in the 1st and 2nd fields (X A, X B or Y C) and pick the one with a highest numerical value in the 3rd field.

So, I expect this output:

X A 10.00
X B 4.00
Y C 2.43

With this snippet I am able to pick the record with max value in the 3rd field (but it's not taking into account the previous fields, and it's not outputting them either):

awk 'BEGIN {max = 0} {if ($2>max) max=$2} END {print max}' input.txt

Current (unwanted) output:

10.00

Any ideas? I can use gawk.

Thanks a lot in advance!

Answer 1

You can use this awk:

awk '{k=$1 OFS $2} $3>a[k]{a[k]=$3} END{for (i in a) print i, a[i]}' file
X A 10.00
X B 4.00
Y C 2.43