GROUP BY/SUM from shell

Question

I have a large file containing data like this:

a 23 b 8 a 22 b 1 

I want to be able to get this:

a 45 b 9 

I can first sort this file and then do it in Python by scanning the file once. What is a good direct command-line way of doing this?

Answer 1

Edit: The modern (GNU/Linux) solution, as mentioned in comments years ago ;-) .

awk '{     arr[$1]+=$2    }    END {      for (key in arr) printf("%s\t%s\n", key, arr[key])    }' file \    | sort -k1,1 

The originally posted solution, based on old Unix sort options:

awk '{     arr[$1]+=$2    }    END {      for (key in arr) printf("%s\t%s\n", key, arr[key])    }' file \    | sort +0n -1 

I hope this helps.