Generate random number without repetition

Comments

• ar2rsawseen Maintainer

  January 2015

  @yubaro I suppose you might have a limit on numbers to generate, like from 1 to 100
  
  then what you can do is to create a table with values from 1 to 100, then get random table element and remove it from table, then again take random element from table, etc.
  
  

  http://appcodingeasy.com/Gideros-Mobile

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• yubaro Member

  January 2015

  Thanks Arturs, you suggest me to do it with an enterFrame event?

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• pie Member

  January 2015 edited January 2015

  @yubaro I'm sorry I am not sure what do you mean by repetition
  you can use math.random and math.randomseed, getting your seed from os.timer() so that it's different on every app start.

  math.randomseed(os.timer()) print(math.random())

  if instead repetition is about the risk to get the same number again inside a loop, like in

  for i=1,20 do number = math.random(1,8) end

  I think you should "save" every number you get in a table, and then manually check if it already exists and act by consequence.
  
  EDIT: ar2sawseen was faster, and maybe had a better solution

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• amin13a Member

  January 2015

  local rnd = {}
  for i = 1, 100 do
  rnd[i] = i
  end
  for i = 1, 100 do
  local rand = math.random(1,100)
  local tmp = rnd[i]
  rnd[i] = rnd[rand]
  rnd[rand] = tmp
  end
  Now You have a random table: rnd
  

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• yubaro Member

  January 2015

  thanks @pie, yes, not get the same number again inside a loop...you suggest me to do it with an enterFrame event?

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• pie Member

  January 2015 edited January 2015

  @yubaro It really depends on what you need and your "big scheme": I would try to avoid onEnterFrame event since it's time based and happens continuously; but I could be wrong.. in some situations it's the only way.
  
  I would do this:
  if you just need it to get all numbers once, use a for
  if you need to get a new number every now and then, use a function that does everything and call it only when it's needed
  if you need a continuous number generation use onEnterFrame. Just keep in mind that it is casted on every frame (30 or 60 times per second - according to your project settings).
  You could also use Timer class if you need more control.
  
  good luck

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• yubaro Member

  January 2015 edited January 2015

  I want my output something like:
  
  local rand = math.random(1,10)
  ....
  --code--
  ....
  print(rand)
  
  output random:
  5
  10
  4
  9
  5..this not, other number
  6
  4
  5..this not, other number
  5..this not, other number
  1
  1..this not, other number
  2
  3
  8
  7
  
  

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• SinisterSoft Maintainer

  January 2015

  Create a table, generate a random number, if the table entry[the random number]==nil then table entry[the random number]=true else generate another random number until done.
  
  It will get slower and slower as the list gets filled up. You could pregenerate the list.
  

  Coder, video game industry veteran (since the '80s, ❤'s assembler), arrested - never convicted hacker (in the '90s), dad of five, he/him (if that even matters!).
  https://deluxepixel.com

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• yubaro Member

  January 2015 edited January 2015

  My problem is I can not solve as generate another random number, until find a different one to that already obtained:
  
  Something, output random:
  5
  10
  4
  9
  5..this not, other number
  6
  4
  5..this not, other number
  5..this not, other number
  1
  1..this not, other number
  2
  3
  8
  7

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• pie Member

  January 2015 edited January 2015

  if you need to random sort a table I would do as @ar2sawseen suggested:
  this, of course, assuming that I understood your needs

  --create a table local tmpTable = {} for i=1,10 do table.insert(tmpTable, i) --insert possible outcome numbers inside the table: at this time the table looks like tmpTable = {1,2,3,...10} end   local function getNum() --get a random index from tmpTable local index = math.random(#tmpTable) --save the value of the number at given index local num = tmpTable[index] --remove index value (table.remove removes the value mantaining index integrity - which is needed to use # - lenght operator) table.remove(tmpTable, index) --return the number return num end   --get your numbers/ your table randomly sorted for q=1, 10 do local number = getNum() print(number) end

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• yubaro Member

  January 2015

  Thanks @pie, is perfect thanks all!

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