awk array: count column return line

Question

I have tried several awk arrays but just can´t get my head around it. Having a file with 4 colums the awk skript should count for each line how many times the value in column 2 appears.

Input File

A1^ABC^173^2012
A2^BDK^153^2013
A3^AFD^223^2012
B1^ABC^083^1999
B2^KLX^033^2012
B3^ABC^593^2003 
B4^KLX^323^2001

So as result I want to print the counter for the value in column 2 at the end of each line. E.g line one has value "ABC" in column2. "ABC" appears 3 times in the entire file and is printed at the end of the line.

Output File

A1^ABC^173^2012^3
A2^BDK^153^2013^1
A3^AFD^223^2012^1
B1^ABC^083^1999^3
B2^KLX^033^2012^2
B3^ABC^593^2003^3
B4^KLX^323^2001^2

Hope anyone got an idea on how to solve it.

Cheers

Steve · Accepted Answer · 2013-11-02 11:35:31Z

4

Here's one way using awk:

awk 'BEGIN { FS=OFS="^" } FNR==NR { a[$2]++; next } { print $0, a[$2] }' file.txt{,}

Results:

A1^ABC^173^2012^3
A2^BDK^153^2013^1
A3^AFD^223^2012^1
B1^ABC^083^1999^3
B2^KLX^033^2012^2
B3^ABC^593^2003^3
B4^KLX^323^2001^2

answered Nov 2, 2013 at 11:35

Steve

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7 Comments

Jotne Over a year ago

What does the {,} do?

Chris Seymour Over a year ago

@Jotne Takes the input file twice, try echo file{,}.

Jotne Over a year ago

Ahh, a new one for me, thanks :) -- {,,,} repeat it three times

Chris Seymour Over a year ago

@EdMorton gnu.org/software/bash/manual/html_node/Brace-Expansion.html

Steve Over a year ago

@EdMorton: Thanks Ed; good question! Please see the 'portability' section here.

|

Chris Seymour · Accepted Answer · 2013-11-02 11:40:32Z

3

The buffered approach:

awk -F'^' -v OFS='^' '{a[NR]=$0;c[$2]++}
    END{for(i=1;i<=NR;i++){split(a[i],b);print a[i],c[b[2]]}}' file

Output:

A1^ABC^173^2012^3
A2^BDK^153^2013^1
A3^AFD^223^2012^1
B1^ABC^083^1999^3
B2^KLX^033^2012^2
B3^ABC^593^2003^3
B4^KLX^323^2001^2

To store the output in a new file use the redirection operator:

awk -F'^' -v OFS='^' '{a[NR]=$0;c[$2]++}
    END{for(i=1;i<=NR;i++){split(a[i],b);print a[i],c[b[2]]}}' file > outfile

answered Nov 2, 2013 at 11:40

Chris Seymour

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2 Comments

anubhava Over a year ago

+1 very good answer, trust me I hadn't seen this while making mine work.

eh2deni Over a year ago

works fine, many thanks. But I´m actually not getting the split and following print section. what is 'b' doing?

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