Use awk to find average of a column [duplicate]

Question

I'm attempting to find the average of the second column of data using awk for a class. This is my current code, with the framework my instructor provided:

#!/bin/awk  ### This script currently prints the total number of rows processed. ### You must edit this script to print the average of the 2nd column ### instead of the number of rows.  # This block of code is executed for each line in the file { x=sum read name         awk 'BEGIN{sum+=$2}'         # The script should NOT print out a value for each line } # The END block is processed after the last line is read END {         # NR is a variable equal to the number of rows in the file         print "Average: " sum/ NR         # Change this to print the Average instead of just the number of rows } 

and I'm getting an error that says:

awk: avg.awk:11:        awk 'BEGIN{sum+=$2}' $name awk: avg.awk:11:            ^ invalid char ''' in expression 

I think I'm close but I really have no idea where to go from here. The code shouldn't be incredibly complex as everything we've seen in class has been fairly basic. Please let me know.

Answer 1

awk '{ sum += $2; n++ } END { if (n > 0) print sum / n; }' 

Add the numbers in $2 (second column) in sum (variables are auto-initialized to zero by awk) and increment the number of rows (which could also be handled via built-in variable NR). At the end, if there was at least one value read, print the average.

awk '{ sum += $2 } END { if (NR > 0) print sum / NR }' 

If you want to use the shebang notation, you could write:

#!/bin/awk  { sum += $2 } END { if (NR > 0) print sum / NR } 

You can also control the format of the average with printf() and a suitable format ("%13.6e\n", for example).

You can also generalize the code to average the Nth column (with N=2 in this sample) using:

awk -v N=2 '{ sum += $N } END { if (NR > 0) print sum / NR }'