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Top Forums UNIX for Dummies Questions & Answers How to randomly select lines from a text file Post 302720825 by Scrutinizer on Wednesday 24th of October 2012 04:49:58 PM
Old 10-24-2012
In the order of lines in the file, without all lines in memory:
Code:
awk '
  NR==FNR { next }
  FNR==1{
    srand;
    n=NR-1
    for(i=1; i<=200; i++) {
      line=0
      while(!line || line in A) line=int(rand*n)+1
      A[line]
    }
  } 
  FNR in A
' infile infile


In the order of the selection, with all lines in the file in memory..
Code:
awk '
  { R[NR]=$0 }
  END{
    srand;
    n=NR
    for(i=1; i<=200; i++) {
      line=0
      while(!line || line in A) line=int(rand*n)+1
      A[line]
      print R[line]
    }
  } 
' infile

 

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IGAWK(1)							 Utility Commands							  IGAWK(1)

NAME
igawk - gawk with include files SYNOPSIS
igawk [ all gawk options ] -f program-file [ -- ] file ... igawk [ all gawk options ] [ -- ] program-text file ... DESCRIPTION
Igawk is a simple shell script that adds the ability to have ``include files'' to gawk(1). AWK programs for igawk are the same as for gawk, except that, in addition, you may have lines like @include getopt.awk in your program to include the file getopt.awk from either the current directory or one of the other directories in the search path. OPTIONS
See gawk(1) for a full description of the AWK language and the options that gawk supports. EXAMPLES
cat << EOF > test.awk @include getopt.awk BEGIN { while (getopt(ARGC, ARGV, "am:q") != -1) ... } EOF igawk -f test.awk SEE ALSO
gawk(1) Effective AWK Programming, Edition 1.0, published by the Free Software Foundation, 1995. AUTHOR
Arnold Robbins (arnold@skeeve.com). Free Software Foundation Nov 3 1999 IGAWK(1)
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