Shell Programming and Scripting

whats up all, I am very happy I joined this forum, I have learned alot just going through.

I have a small dilemma... trying to parse a textfile, and sort by 1st feild and add up second feild....

cat textfile.in

1200, 2.50
1200, 1.00
1200, 3.00
1000, 1.00
1000, 2.00
1500, 10.00
1600, 1.00
1600, 2.00

what I need is for this file to look like this...
1200, 6.50
1000, 3.00
1500, 10.00
1600, 3.00


The way I know how to do this involves grep and tmpfiles, takes a long time, and is basically a big mess.... I wanna know if someone knows like a one line apprach do doing this.

for list in `cat textfile.in | awk -F, '{print $1}' | sort | uniq`
do
>$$.tmp
grep $list textfile.in | awk -F, '{print $2}' >> $$.tmp
# Internal utilty sumfeld adds contents of given feild
totalprice=`sumfld $$.tmp 1`
echo "${list},${totalprice}" >> newfile.txt
done

How about an awk script...

Code:

awk -vOFMT=%.2f '{
           if (first == 0) { first=1 ; save=$1 ; tot=0 }
           if (save != $1) { print save, tot ; save=$1 ; tot=0 }
           tot+=$2 }
    END    { print save, tot}'

another way to look at this would be to use perl.

populate a hash 1 element at a time.
for each new line split it up into 2 variables (ie: $column1, $column2) then check the hash for an exhisting key that is equal to $column1.

if you dont have a key already then add $column1 and $column2 as the key value pair.

if it does exhists get the value for that key and add it to $column2.

once your files is done being read your hash will only have uniq keys. and your values will be added together.

Using an array in awk...

awk '{a[$1]+=$2}END{for(i in a)printf "%s %.2f\n",i,a[i]}' textfile.in

Just for Optimus_P, I ran the awk snippet thru ap2, the awk to perl converter.../

Code:

while (<>) {
    ($Fld1,$Fld2) = split(' ', $_, 9999);
    $a{$Fld1} += $Fld2;
}

foreach $i (keys %a) {
    printf "%s %.2f\n", $i, $a{$i};
}

I have a solution which is similar to what perdarabo posted.

sort -n file | awk '$1==prev {sum+=$2;} $1!=prev {if(NR!=1) print prev, sum;sum=$2; prev=$1;} END {print prev, sum}'