CODEWITHSUNDEEP
bashawk
719016
719016

Reputation: 10431

awk calculate average or zero

I am calculating the average for a bunch of numbers in a bunch of text files like this:

grep '^num' file.$i | awk '{ sum += $2 } END { print sum / NR }'

But some times the file doesn't contain the pattern, in which cas I want the script to return zero. Any ideas of this slightly modified one-liner?

Upvotes: 9

Views: 7526

Answers (3)

shellter
shellter

Reputation: 37258

Use awk's ternary operator, i.e. m ? m : n which means, if m has a value '?', use it, else ':' use this other value. Both n and m can be strings, numbers, or expressions that produce a value. 

grep '^num' file.$i | awk '{ sum += $2 } END { print sum ? sum / NR : 0.0 }'

Upvotes: 2

JRFerguson
JRFerguson

Reputation: 7516

You're adding to your load (average) by spawning an extra process to do everything the first can do. Using 'grep' and 'awk' together is a red-flag. You would be better to write:

awk '/^num/ {n++;sum+=$2} END {print n?sum/n:0}' file

Upvotes: 17

mouviciel
mouviciel

Reputation: 67831

Try this:

... END { print NR ? sum/NR : 0 }

Upvotes: 5

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