Calculate sum of column using reference of other column in awk

Question

I have a file which contains 2 column. first column contains some keyword and second contains its size. Keywords can be repeated like below:

data1 5
data2 7
data         


        

Answer 1

If you want to keep output in same order as the input then use this little longer awk:

awk '$1 in a{a[$1]+=$2; next} {b[++k]=$1; a[$1]=$2}
             END{for(i=1; i<=k; i++) print b[i], a[b[i]]}' file
data1 8
data2 21
data3 4