Random numbers without repetition

asal_email · #1 (**permalink**) 07-13-2005

Is anyone know some scripts to generate random number without repetition using bash; for example generate 10 different random numbers.

Thanks

Ygor · #2 (**permalink**) 07-13-2005

Try...

Code:

awk -v loop=10 -v range=100 'BEGIN{
  srand()
  do {
    numb = 1 + int(rand() * range)
    if (!(numb in prev)) {
       print numb
       prev[numb] = 1
       count++
    }
  } while (count<loop)
}'

asal_email · #3 (**permalink**) 07-13-2005

Thanks, great code !!! but I need some clarifications.

when you compare the generated number to previous one, using :
if (!(numb in prev))
isn't comparing only the last generated random number with the current one or comparing all previous generated random number ? so only uniq number retained.

Thanks

Ygor · #4 (**permalink**) 07-13-2005

The code compares all previously generated numbers which are stored in an array called 'prev'.

r2007 · #5 (**permalink**) 07-14-2005

Select 10 numbers from 1 through 80

Code:

for (( i=1;i<=80;i++ )) do echo $RANDOM $i; done|sort -k1|cut
 -d" " -f2|head -10

it works using bash

asal_email · #6 (**permalink**) 07-14-2005

I actually want to use those random number on the fly such :
#! /bin/bash
while (condition)
do
number=$RANDOM
do some work here using random number until condition satisfied
done

the condition is independent of generated random number
but random numbers have to be generated as along as condition is met and
all numbers generated have to be unique.

Thanks again

r2007 · #7 (**permalink**) 07-14-2005

Quote:

Originally Posted by asal_email

I actually want to use those random number on the fly such :
#! /bin/bash
while (condition)
do
number=$RANDOM
do some work here using random number until condition satisfied
done

the condition is independent of generated random number
but random numbers have to be generated as along as condition is met and
all numbers generated have to be unique.

Thanks again

well, the bash variable "$RANROM" is a random integer between 0 and 32767. if the condition is independent of generated random number, try to imagine the loop block has already run 32768 cycles, all of numbers used up.

so the condition must consider the random numbers rang.

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