Randomly shuffling of array elements

hussain.s · 10-10-2010, 04:02 AM

hi
i have an array var=(node1,node2,node3,node4) and i want to shuffle the array elements randomly every time when unix script will run like that.....

first time when script run order will be shuffle randomly
node3,node1,node4,node2

second time when script run order will be shuffle randomly like
node1,node4,node2,node3

third time when script will run again order will be shuffle randomly like
node2,node1,node3,node4

how to do this without using of shuf or shufsequence commands

please do the needful

mario.almeida · 10-10-2010, 05:23 AM

Hi,

May be this can help you.

http://www.linuxquestions.org/questi...2/#post4122764

mario.almeida · 10-10-2010, 06:02 AM

Well,

First of all you need to update your own post.

Up to my knowledge I don't think I can do that with bash.

declare -a temp
temp=($(echo node1,node2,node3,node4 | tr ',' '\n' | awk 'BEGIN { srand() } { print rand() "\t" $0 }' | sort -n | cut -f2- ))

above temp will hold it as an array

hussain.s · 10-11-2010, 12:33 AM

hi,
thanks for your solution but is it possible that we can do the randomly shuffling of array elements without using of awk file

hussain.s · 10-11-2010, 01:16 AM

hi,
the below is my code
in this code my A2 file have some values like test1,test2,test3 etc and in the temp variable iam randomly shuffling the order of A2 file elements each time when running the script
like one time when run the script it shuffle the order randomly
test2,test3,test1
second time when script run again it shuffle the order randomly
test3,test1,test2
like that each time when script is running it shuffle the order randomly

now i want to pass the temp variable which have A2 file value to the another file A3 iam able to pass the value but it is always showing the same order when every time iam running the script but i want that each time when script will run value of file A3 should be changed randomly when A2 file value should be shuffled randomly because indirectly iam passing the A2 file value to the A3 file

please do the neeful

#!/bin/sh
APP_INSTANCE_ID=56
file1=/Users/hussain/Desktop/shells/A2 //here A2 is the text file which have value test1,test2,test3
file2=/Users/hussain/Desktop/shells/A3 ////A3 is the text file in which A2 file value is coming
id=`cat $file1 | cut -d "=" -f 2`

temp=$(echo $id | tr ',' '\n' | awk 'BEGIN { srand() } { print rand() "\t" $0 }' | sort -n | cut -f2- | tr '\n' ',' | sed 's/,$//')

echo "$temp"

sed "s/$temp//g" $temp > $l_tmp_web_config_file2 //in this line value of A2 is coming in the A3 file but it is
always showing the same order each time when script is running

hussain.s · 10-11-2010, 09:32 AM

hi,
this is my file1 which have below contents
test=test1,test2,test3,test4,test5
hi
hello
world

now i want to display the contents of file1 into another file2 here file1 contents of first line is shuffling randomly i want the output like that each time when script will run
first time when script run
test=test2,test1,test3,test4,test5//here value is randomly shuffling
hi
hello
world

second time when script will run
test=test4,test3,test2,test1,test5//here value is again randomly shuffling
hi
hello
world

but when iam running the script output is comming like that
test=test4,test3,test2,test1,test5,hi,hello,world
is there any solution

mario.almeida · 10-11-2010, 10:14 AM

Hi,

May be you can try something like this.

Save the below output to a file format.sh

Code:

#!/bin/bash

file="$1"
[[ ! -f "$file" ]] && exit 0
declare -i lineCount=$(wc -l < $file)

oldRandNo=$(( $lineCount+2 ))

for (( i=1; i<=$lineCount; i++)); do
        declare -a wc_array=($(sed -n "${i}p" $file | tr ',' ' '))

        wc_count=${#wc_array[@]}

        if [[ $wc_count -gt 0 ]]; then
                randNo=$((RANDOM % $wc_count))
                if [[ $randNo -eq $oldRandNo ]]; then
                        if [[ $randNo -eq 0 ]]; then
                                randNo=$(( $wc_count-1 ))
                        else
                                randNo=$((RANDOM % $wc_count))
                                if [[ $randNo -eq $(( wc_count-1 )) ]]; then
                                        randNo=0
                                else
                                        randNo=$(( randNo+1 ))
                                fi
                        fi
                fi
        else
                continue
        fi


        string="${wc_array[$randNo]} "

        for (( y=0; y<$wc_count; y++ )); do
                [[ $y -ne $randNo ]] && string+="${wc_array[$y]} "
        done
        echo $string | tr -s '[:blank:]' | sed 's/ /,/g'
        oldRandNo=$randNo
done

Quote:

sh format.sh file1

David the H. · 10-11-2010, 11:03 AM

hussain.s, please use [code][/code] around your code, to preserve formatting and to improve readability.

Here's a bash-builtin only way to shuffle array elements. I wouldn't try it on very large arrays though, as it uses a simple brute-force testing loop to keep it from creating duplicates. I used the comma-separated input list given above.

Code:

IFS=","
test="test1,test2,test3,test4,test5"
array1=( $test )

num=${#array1[@]}
complete=""

for i in  ${!array1[@]}; do
     while true; do
          newi=$(( RANDOM%num ))

          if [[ ! $complete =~ "$newi:" ]]; then
               array2[$newi]="${array1[$i]}"
               complete="${complete}${newi}:"
               break
          fi
     done
done

echo "${array2[*]}"
# [#] here will the entire array as a single string, using the current IFS as separator.  Commas in this case.  Must be quoted.
# [@] will print each element individually separated by spaces.

There are probably better ways to do it.

David the H. · 10-11-2010, 02:47 PM

I just discovered that there's a gnu coreutils application called shuf that can be used to randomize an input sequence. Here's a greatly simplified version of my last script that uses it.

Code:

teststring="test1,test2,test3,test4,test5,test6"
array1=( ${teststring//,/ } )

num=$(( ${#array1[@]} -1 ))
newseq=$( shuf -i 0-$num )

for i in $newseq; do

     outstring+="${array1[$i]},"

done

echo ${outstring%,}

Much cleaner overall, although it does now depend on an external tool. But at least that tool is a core utility. You'll notice I've also eliminated messing around with the IFS.