Awk script: loop through rows and get sum

Question

I am putting together a (g)awk file script that loops through the numeric data provided from in an input file, and has to sum the values in each row. I am creating an array and adding the row sums to each array position. Below is my code. The logic seems ok, but the output is off:

for(i = 1; i <= NF; ++i){
   for(j = 1; j <= NR; ++j){
       row[i] += $j
   }
}

fedorqui · Accepted Answer · 2015-08-04 12:29:43Z

4

You cannot loop through the lines. The loop through lines is done implicitly done by awk while reading the file.

So you just need to update the values in an array for the current line:

awk '{for (i=1;i<=NF;i++) a[i]+=$i}' file

Then, you can print the summary within the END block.

See an example:

$ cat a
1 2 3 4 5
6 7 8 9 10
$ awk '{for (i=1;i<=NF;i++) a[i]+=$i} END {for (i in a) print i " -> " a[i]}' a
1 -> 7
2 -> 9
3 -> 11
4 -> 13
5 -> 15

answered Aug 4, 2015 at 12:29

fedorqui

293k113 gold badges592 silver badges640 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

cadebe Over a year ago

Thank you for reminding me. A follow up on you answer: your example indicates the way to obtain column totals. I still can't figure out how to sum ROWS correctly. I find I don't get the expected results when I use the record number value: {for(i = 1; i <=NR;++i) rows[i] += $i}, as I would have expected.

fedorqui Over a year ago

@user2781042 Not sure what you mean with "sum rows": sum all the elements in a row? If this is the case, something like awk '{sum=0; for (i=1;i<=NF;i++) sum+=$i; print sum}' file makes it.

Collectives™ on Stack Overflow

Awk script: loop through rows and get sum

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related