bash add up columns with same first column

Question

I have a file that has a name in the first column and count in the second column. It is sorted by name.

    dan 3355
    dan 667
    dan 889
    frank 8
    frank 99
    frank 90
    ian 9

I would like to combine all the same names and output the total count for each name:

    dan 4911
    frank 197
    ian 9

I know that I can use uniq for getting a total count of the identical lines, but how can I preserve the counts that I have in my data?

Answer 1

You can make use of awk's associative array:

 awk '{arr[$1]+=$2;} END {for (i in arr) print i, arr[i]}' filename

Answer 2

Using awk's associative memory does not guarantee that names will appear in output in the same order as in input (and may be memory inefficient for large data sets).

Use the following instead

awk '(NR==1){oldname=$1;s=$2;next};
     (oldname == $1){s=s+$2;next};
     {print oldname, s;oldname=$1s=$2;next}
     END{print oldname,s}'