# Lib - generating a list of random number **URL:** \ **Category:** Ruby\ **Created:** [November 14, 2006, 5:12pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944 "2006-11-14T17:12:56Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 5:12pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/1 "2006-11-14T17:12:56Z")
I try to generate an array of N random numbers in range between 2 integers min and max but I don’t understand very well how to coordinate the sue of srand and rand… is there an already written function for that ? and btw is there any place to find such useful functions ? thanks joss ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 5:34pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/2 "2006-11-14T17:34:58Z")
On Wed, 15 Nov 2006, Josselin wrote: > harp:~ \> cat a.rb n, max, min = 42, 10, 6 p Array.new(n).map{ rand((max - min) + 1) + min} harp:~ \> ruby a.rb [6, 8, 8, 10, 9, 7, 6, 8, 9, 7, 10, 10, 7, 7, 9, 9, 6, 9, 10, 6, 8, 10, 6, 9, 7, 8, 8, 10, 8, 9, 9, 9, 10, 7, 9, 6, 6, 8, 8, 10, 9, 7] -a ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 5:36pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/3 "2006-11-14T17:36:59Z")
On 14.11.2006 17:09, Josselin wrote: > I try to generate an array of N random numbers in range between 2 > integers min and max > but I don’t understand very well how to coordinate the sue of srand and > rand… I am not sure I understand you here. What does “sue” mean here? > is there an already written function for that ? and btw is there any > place to find such useful functions ? What about this? > > def rand\_seq(count, min, max) > > (1…count).map { rand(max-min) + min } > > end > > =\> nil > > > rand\_seq 10, -5, 5 > > =\> [2, -4, -2, -1, -3, 1, 1, 1, -3, 0] Kind regards ``` robert ``` ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 7:11pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/4 "2006-11-14T19:11:27Z")
On 2006-11-14 17:30:31 +0100, Robert K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) said: > What about this? > robert > sorry sue =\> usage… typing mistake… thanks !!! that’s exactly what I searched for… I knew how to generate an array with an ‘upper limit only’ … ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 6:21pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/5 "2006-11-14T18:21:14Z")
Josselin wrote: > I try to generate an array of N random numbers in range between 2 > integers min and max > but I don’t understand very well how to coordinate the sue of srand and > rand… They are very easy to use, but first you have to decide what you want to do. What do you want to do? What role does “srand()” play? Be specific. > is there an already written function for that ? For what, specifically? The range of random numbers, or the use of “srand()”? If you always want the same sequence of random numbers, then there is one solution, but if you always want a different sequence, there is a different solution. Which do you want? > and btw is there any > place to find such useful functions ? There sure is: > **[Ruby-Doc.org: Documenting the Ruby Language](https://ruby-doc.org/)** > > Fast, searchable Ruby documentation for core and standard libraries. Plus, links to tutorials, guides, books, and related sites. By the way, when you ask a question like this, it is best to express your requirement as specifically as possible. You may have noticed that you got two different replies to your inquiry, each with sample code that provided differing interpretations of your request. The solution to this problem is to leave no doubt about your requirement. For example, when you say “between two integers” do you mean: a \< n \< b or a \<= n \<= b or some third possibility? ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 7:21pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/6 "2006-11-14T19:21:28Z")
On 2006-11-14 18:17:19 +0100, Paul L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) said: > > is there an already written function for that ? > > [http://www.ruby-doc.org/](http://www.ruby-doc.org/) > > thanks > > or > a \<= n \<= b > > or some third possibility? I apologize… I was looking for a result (how to generate a list of random integer numbers between a minimum and a maximum … included) … yes forgotten to specify including limits… and at the same time trying to understand how to USE srand()and rand(), my standard Ruby manual is clearly written but there is no example for this function. I googled a lot but without any success regarding examples… my first thought was: srand() is useful in setting a limit to the generator… used by rand() so it could have been a clue to solve my problem… ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 7:31pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/7 "2006-11-14T19:31:30Z")
On Wed, 15 Nov 2006, Josselin wrote: > I googled a lot but without any success regarding examples… > my first thought was: srand() is useful in setting a limit to the > generator… used by rand() so it could have been a clue to solve my > problem… Use [ruby-doc.org](http://ruby-doc.org) [http://ruby-doc.org/core/classes/Kernel.html#M002012](http://ruby-doc.org/core/classes/Kernel.html#M002012) Kirk H. ---
**Author:** ![Josselin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@Josselin](https://www.ruby-forum.com/u/Josselin)\ **Post date:** [November 14, 2006, 9:11pm UTC](https://www.ruby-forum.com/t/lib-generating-a-list-of-random-number/75944/8 "2006-11-14T21:11:58Z")
Josselin wrote: / … > and at the same time trying to understand how to USE srand()and rand(), > my standard Ruby manual is clearly written but there is no example for > this function. > I googled a lot but without any success regarding examples… > my first thought was: srand() is useful in setting a limit to the > generator… used by rand() so it could have been a clue to solve my > problem… All except you haven’t yet said what the problem is. We could solve a stated problem, easily. srand() sets a particular starting point for a pseudorandom sequence. If you use srand() and supply a fixed argument, you will get the same pseudorandom sequence on each run of your program: * * * #!/usr/bin/ruby -w ## 4.times do srand(1) 10.times do print "#{rand(16)} " end puts end Notice about this program that it puts out the same sequence every time. Now comment out the “srand(1)” line and see the difference.