How can I make a script that awk .txt files with spaces to read .csv?

Question

I have a code that extracts from the following table (testtam.txt)

gene1   1   3   5   9           
gene2   0   0   4   4           
gene3   1   0   1   2           
gene4   5   5   0   10          
gene5   2   0   0   2   

the rows where only one of fields 2, 3 or 4 have a value that is not 0 and saves them into a separate file (match-file):

awk '{
    if (    ($2 == $5 && $3 == 0 && $4 == 0) || \
        ($2 == 0 && $3 == $5 && $4 == 0) || \
        ($2 == 0 && $3 == 0 && $4 == $5) ) {
        print $0 > "match-file"
}   else if ($2 + $3 + $4 == $5) {
        print $0 > "nomatch-file"
     }    
}' testtam.txt

The problem is that is does not work with .csv files, e.g. if I have that kind of .csv table

gene1,1,3,5,9           
gene2,0,0,4,4           
gene3,1,0,1,2           
gene4,5,5,0,10          
gene5,2,0,0,2

awk recognizes it as a one single column.

How can I make my code read columns from .csv?

Answer 1

You just need to use a different field-delimiter. That's what awk's -F option dos:

awk -F',' '{
    if (    ($2 == $5 && $3 == 0 && $4 == 0) || \
        ($2 == 0 && $3 == $5 && $4 == 0) || \
        ($2 == 0 && $3 == 0 && $4 == $5) ) {
        print $0 > "match-file"
}   else if ($2 + $3 + $4 == $5) {
        print $0 > "nomatch-file"
     }    
}' 

or, if what you want is to match those lines where at least two of the fields from the 2nd till the last have values that are not 0, you could just do:

awk -F, '{ 
            c=0; 
            for(i=2;i<=NF-1;i++){ 
                c+= $i!=0
            } 
            print > ((c > 1) ? 
                "match-file" : 
                "nomatch-file")
          }' file