Merging columns from two separate files

How to create a new file merging selective columns from two separate files using awk? Without messing up the elements orders of BOTH files.

Exemple: File 3 may contain column 1,2,3 from File 1 and column 4 from File 2.

File 1
A   23  8   T
A   63  9   9
B   45  3   J

File 2
A   0
A   6   
B   5

File 3
A   23  8   0
A   63  9   6
B   45  3   5

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Answers:

Method 1

Method 2

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

There’s a dedicated tool for that: paste. It concatenates each full line from the first file with the corresponding line from the second file; you can remove unwanted columns before or after. For example, assuming that your columns are tab-delimited:

paste file1.txt file2.txt | cut -f 1,2,3,6

Here’s a way to pre-filter both files that relies on ksh/bash/zsh process substitution.

paste <(<file1.txt sed 's/[[:space:]][[:space:]]*[^[:space:]]*$//') 
      <(<file1.txt sed 's/^[^[:space:]]*[[:space:]][[:space:]]*//')

Awk is primarily geared to processing one file at a time, but you can call getline to read from another file in parallel.

awk '
  BEGIN {file2=ARGV[2]; ARGV[2]="";}
  {$0 = $0 ORS getline(); print $1, $2, $3, $6;}
' file1.txt file2.txt

So far I’ve assumed that you want to match line 1 of file 1 with line 1 of file 2, line 2 of file 1 with line 2 of file 2, etc. If you want to match the contents of a column, that’s a completely different matter. join will do the job provided that the column you want to match is sorted.

Method 2

Try this:

$ awk 'FNR==NR{a[FNR]=$2;next};{$NF=a[FNR]};1' file2 file1
A 23 8 0
A 63 9 6
B 45 3 5

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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