Use awk to find average of a column

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

User · Answer

Try this   ls -l    awk -F     sum   5  END  print  AVG   sum NR     NR is an AWK builtin variable to count the no  of records

User · Answer

awk    sum     2  n     END   if  n  gt  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  gt  0  print sum   NR      If you want to use the shebang notation  you could write      bin awk    sum     2   END   if  NR  gt  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  gt  0  print sum   NR

User · Answer

awk  s   2 print s NR   table   tail -1   I am using tail -1 to print the last line which should have the average number

User · Answer

Your specific error is with line 11   awk  BEGIN sum   2     This is a line where awk is invoked  and its BEGIN block is specified - but you are already within a awk script  so you do not need to specify awk  Also you want to run sum   2 on each line of input  so you do not want it within a BEGIN block  Hence the line should simply read   sum   2   You also do not need the lines   x sum read name   the first just creates a synonym to sum named x and I m not sure what the second does  but neither are needed   This would make your awk script      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       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     Jonathan Leffler s answer gives the awk one liner which represents the same fixed code  with the addition of checking that there are at least 1 lines of input  this stops any divide by zero error   If

[bash] Use awk to find average of a column

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