awk division error - 0


 
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# 1  
Old 12-24-2010
awk division error - 0

input
Code:
0	0	9820373	2069	0	0	11485482

Code:
awk '{print ($1/$3) / ($4/$7)}' input

error
Quote:
awk: division by zero
input record number 1, file input
source line number 1
Is there any way to fix this problem ?
# 2  
Old 12-24-2010
are you sure you have typed correct input? Because on my computer it works and results to 0:
Code:
>awk '{print ($1/$3) / ($4/$7)}'
0       0       9820373 2069    0       0       11485482
0

Anyway you may check whether the divisor is equal to 0 and skip such lines or produce 0 without performing any divisions.
# 3  
Old 12-24-2010
some of the lines are actually 0.22 or some thing. I'm still getting the same error
# 4  
Old 12-24-2010
Looks like in some reocrds, $3/$7 is missing or zero, you may verify this using below:
Code:
awk '{if(!$3 || $3==0 || !$7 || $7==0) print}' input

# 5  
Old 12-24-2010
if you want to have as the result 0 instead of fatal error you may use the following:
Code:
>awk '{_div1= $3 ? ($1 / $3) : 0 ; _div2 = $7 ? ( $4 / $7 ) : 0; _res = _div2 ? ( _div1 / _div2 ) : 0 ; print _res }'
0 0 0 0 0 0 0 0 0 0 0 0 
0
0.2 0.2 0.2 0.2 0.2 0.2 0.2
1
1 2 3 4 5 6 7 8 
0.583333

If you need, I can send you the explanation
# 6  
Old 12-24-2010
May be I haven't explained well enogu. Here is my real example.
I have 73 sets, each set containing 4 columns (example red and blue) and unique header.

input
Code:
gName	1_rawcounts	1_KPM	1.ed(all reads)	1_total_length	21_rawcounts	21_KPM	21.ed(all reads)	21_total_length
E3_c1-	0	0	8820373	2069	0	0	11485482	2069
E3_c2-	0	0	8820373	2069	0	0	11485482	2069
E3_c3-	0	0	8820373	2069	0	0	11485482	2069
E3_c4-	0	0	8820373	2069	0	0	11485482	2069

Code:
awk '{print ($2/$5) / ($4 / $5) "\t" ($6/$9) / ($8/$9)}' input

needed output
Code:
gName	1	21
E3_c1-	0	0
E3_c2-	0	0
E3_c3-	0	0
E3_c4-	0	0


Last edited by quincyjones; 12-24-2010 at 07:21 PM..
# 7  
Old 12-25-2010
The first line in the file is the header, so you need to skip it
Code:
awk 'NR>1{print $1 "\t" ($2/$5) / ($4 / $5) "\t" ($6/$9) / ($8/$9)}' infile

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