CODEWITHSUNDEEP
awk
Averi
Averi

Reputation: 13

AWK command to multiple all columns of first two rows

I have a file with many columns and three rows. I am trying to multiply the only first two rows (all of the columns in these rows) by -1 to flip their signs. New to coding so bear with me please, I've been googling around for a while now and I'm still confused.

So far what I have:

awk 'NR==1 {print $0*-1} NR==2 {print $0*-1}' filename

Any guidance is much appreciated. Here's a sample of the data...

0 0.6548 0.2719 -0.7817, etc
0 -0.355659 -0.933965 -0.152743 -0.110437, etc 
0 0.666817 0.231877 -0.179657 0.986756 -0.127037 0.377155, etc (3 rows, about 50 columns)

Upvotes: 1

Views: 155

Answers (1)

Raman Sailopal
Raman Sailopal

Reputation: 12867

awk 'NR < 3 { for (i=1;i<=NF;i++) { $i=$i*-1 } }1' > filename.tmp && cp -f filename.tmp filename && rm -f filename.tmp

Where the number record is less than third, loop from 1 to number of fields (NF) setting the field ($i) equal to the field * -1. Use short hand 1 to print the line

I've assumed a space for the delimiter. Change accordingly if necessary with awk -F

Upvotes: 2

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