"How to randomly select lines from a text file"

Post #302720825 by Scrutinizer on Wednesday 24th of October 2012 04:49:58 PM

In the order of lines in the file, without all lines in memory:
awk '
  NR==FNR { next }
    for(i=1; i<=200; i++) {
      while(!line || line in A) line=int(rand*n)+1
  FNR in A
' infile infile

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

Test Your Knowledge in Computers #734
Difficulty: Medium
Commodore BASIC was also known as PET BASIC.
True or False?

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

how to select a value randomly

on my desktop i am using the kde rotating desktop image option. this rotates images randomly every half hour. now, i would like to write an html file which will have an inline frame with some text, maybe system messages, or my friends live journal thati read alot, or unix.com! however, i dont want... (1 Reply)
Discussion started by: norsk hedensk
1 Replies

2. AIX

Randomly appearing control characters in text files

Hi, From some time, we have noticed that our ascii files have started corrupting due to the presence of some random control characters (^@, ^M, ^H, ^D). The characters appear randomly on any file after the process that creates the file finishes. If we rerun the process, the files re creates... (0 Replies)
Discussion started by: aakashahuja
0 Replies

3. UNIX for Dummies Questions & Answers

Select only certain lines from file and mantain formatting

I want to take the below data, and have it output to file only the STMC#/(IP address) and the "there are X number of updates to install" lines for each machine. I know it's easy, but Im a beginner in BASH stuff, my solution would probably take way too many lines to do something easy.Thanks! ... (5 Replies)
Discussion started by: glev2005
5 Replies

4. Shell Programming and Scripting

Select some lines from a txt file and create a new file with awk

Hi there, I have a text file with several colums separated by "|;#" I need to search the file extracting all columns starting with the value of "1" or "2" saving in a separate file just the first 7 columns of each row maching the criteria, with replacement of the saparators in the nearly created... (4 Replies)
Discussion started by: capnino
4 Replies

5. Shell Programming and Scripting

Select lines in which column have value greater than some percent of total file lines

i have a file in following format 1 32 3 4 6 4 4 45 1 45 4 61 54 66 4 5 65 51 56 65 1 12 32 85 now here the total number of lines are 8(they vary each time) Now i want to select only those lines in which the values... (6 Replies)
Discussion started by: vaibhavkorde
6 Replies

6. Shell Programming and Scripting

randomly shuffle two text files the same way

What I have are two text files that I need to shuffle randomly, but I need the two files to be randomly shuffled the same way. I have heard of shuf but I do not know how to use it for two files. Maybe there is also an easy/simple awk command I do not know about that could handle this problem. ... (3 Replies)
Discussion started by: adrunknarwhal
3 Replies

7. Shell Programming and Scripting

Get 20% of lines in File randomly

Hello, This is my code: nb_lignes=`wc -l $1 | cut -d " " -f1` for i in $(seq $nb_lignes) do m=`head $1 -n $i | tail -1` //command done Please how can i change it to get Get 20% of lines in File randomly to apply "command" on each line ? 20% or 40% or 60 % (it's a parameter) Thank you. (15 Replies)
Discussion started by: chercheur857
15 Replies

8. Shell Programming and Scripting

Select lines from a file based on a criteria

Hi I need to select lines from a txt file, I have got a line starting with ZMIO:MSISDN= and after a few line I have another line starting with 'MOBILE STATION ISDN NUMBER' and another one starting with 'VLR-ADDRESS' I need to copy these three lines as three different columns in a separate... (3 Replies)
Discussion started by: Tlcm sam
3 Replies

9. Shell Programming and Scripting

How to select lines randomly without replacement in UNIX?

Dear Folks I have one column of 15000 lines and want to select randomly 5000 of them in five different times without replacement. I am aware that command 'shuf' and 'sort -R' could select randomly those lines but I am not sure how could I avoid the replacement of selection line. Does anyone have... (10 Replies)
Discussion started by: sajmar
10 Replies

10. Shell Programming and Scripting

Match text to lines in a file, iterate backwards until text or text substring matches, print to file

hi all, trying this using shell/bash with sed/awk/grep I have two files, one containing one column, the other containing multiple columns (comma delimited). file1.txt abc12345 def12345 ghi54321 ... file2.txt abc1,text1,texta abc,text2,textb def123,text3,textc gh,text4,textd... (6 Replies)
Discussion started by: shogun1970
6 Replies
PRUNEHISTORY(8) 					      System Manager's Manual						   PRUNEHISTORY(8)

prunehistory - remove file names from Usenet history file SYNOPSIS
prunehistory [ -f filename ] [ -p ] DESCRIPTION
Prunehistory modifies the history(5) text file to ``remove'' a set of filenames from it. The filenames are removed by overwriting them with spaces, so that the size and position of any following entries does not change. Prunehistory reads the standard input. The input is taken as a set of lines. Blank lines and lines starting with a number sign (``#'') are ignored. All other lines are should consist of a Message-ID followed by zero or more filenames. The Message-ID is used as the dbz(3) key to get an offset into the text file. If no filenames are mentioned on the input line, then all filenames in the text are ``removed.'' If any filenames are mentioned, they are converted into the history file notation. If they appear in the line for the specified Message-ID then they are removed. Since innd(8) only appends to the text file, prunehistory does not need to have any interaction with it. OPTIONS
-p Prunehistory will normally complain about lines that do not follow the correct format. If the ``-p'' flag is used, then the program will silently print any invalid lines on its standard output. (Blank lines and comment lines are also passed through.) This can be useful when prunehistory is used as a filter for other programs such as reap. -f The default name of the history file is <pathdb in inn.conf>/history; to specify a different name, use the ``-f'' flag. HISTORY
Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews. This is revision 1.7, dated 1998/04/09. SEE ALSO
dbz(3), history(5), inn.conf(5), innd(8). PRUNEHISTORY(8)

Featured Tech Videos

All times are GMT -4. The time now is 10:12 AM.
Unix & Linux Forums Content Copyright 1993-2019. All Rights Reserved.
Privacy Policy