[#345382] Nice algorithm for 'spreading' indexes across an array? — Max Williams <toastkid.williams@...>

Little ruby algorithm puzzle...

13 messages 2009/09/01

[#345437] clogger 0.0.4 - configurable request logging for Rack — Eric Wong <normalperson@...>

* http://clogger.rubyforge.org/

10 messages 2009/09/02
[#345439] Re: [ANN] clogger 0.0.4 - configurable request logging for Rack — Iñaki Baz Castillo <ibc@...> 2009/09/02

2009/9/2 Eric Wong <normalperson@yhbt.net>:

[#345446] rdoc — Oleg Puchinin <ruby_talk@...>

Hello !

17 messages 2009/09/02
[#346260] Ruby 1.9 rdoc never ends (Re: rdoc) — James Britt <james.britt@...> 2009/09/12

Oleg Puchinin wrote:

[#346267] Re: Ruby 1.9 rdoc never ends (Re: rdoc) — Ryan Davis <ryand-ruby@...> 2009/09/12

[#346276] Re: Ruby 1.9 rdoc never ends (Re: rdoc) — Roger Pack <rogerpack2005@...> 2009/09/12

Ryan Davis wrote:

[#345493] What licensing info is needed in code headers? — "Shot (Piotr Szotkowski)" <shot@...>

Disclaimer: I know that some of you live in jurisdictions that do not

10 messages 2009/09/02

[#345535] Simple New Ruby Programmer Problem with $stdin.gets — Mason Kelsey <masonkelsey@...>

I'm having difficulty getting any command to work to pick up input from a

14 messages 2009/09/02

[#345573] Type checking function parameters — Nick Green <cruzmail.ngreen@...>

More or less all my functions look something like

22 messages 2009/09/03
[#345593] Re: Type checking function parameters — Eleanor McHugh <eleanor@...> 2009/09/03

On 3 Sep 2009, at 05:04, Nick Green wrote:

[#345606] Re: Type checking function parameters — Paul Smith <paul@...> 2009/09/03

My first stab at some Ruby started like this too.

[#345667] Re: Type checking function parameters — Nick Green <cruzmail.ngreen@...> 2009/09/03

OK...

[#345676] Re: Type checking function parameters — Eleanor McHugh <eleanor@...> 2009/09/04

On 3 Sep 2009, at 23:47, Nick Green wrote:

[#345687] Re: Type checking function parameters — James Edward Gray II <james@...> 2009/09/04

On Sep 3, 2009, at 7:30 PM, Eleanor McHugh wrote:

[#345745] Re: Type checking function parameters — Eleanor McHugh <eleanor@...> 2009/09/04

On 4 Sep 2009, at 03:56, James Edward Gray II wrote:

[#345828] Re: Type checking function parameters — spiralofhope <spiralofhope@...> 2009/09/06

Along the lines of this thread..

[#345835] Re: Type checking function parameters — "David A. Black" <dblack@...> 2009/09/06

Hi --

[#345773] Rubyscript instead of javascript — Damjan Rems <d_rems@...>

30 messages 2009/09/05
[#345970] Re: Rubyscript instead of javascript — Jg W Mittag <JoergWMittag+Usenet@...> 2009/09/08

David Masover wrote:

[#345774] how to compare two object instances? is "m1.to_yaml.eql?(m2.to_yaml)" a good way? — Greg Hauptmann <greg.hauptmann.ruby@...>

Hi,

8 messages 2009/09/05

[#345848] i need to strip \n and nil — Bigmac Turdsplash <i8igmac@...>

im sending files back and forth form a client and a server using

16 messages 2009/09/06

[#345883] Executing system commands in threads under Ruby 1.8.6 — vhaerun vh <etaern@...>

I tried to write a script that makes use of external binaries. Each

17 messages 2009/09/07
[#345889] Re: Executing system commands in threads under Ruby 1.8.6 — Robert Klemme <shortcutter@...> 2009/09/07

2009/9/7 vhaerun vh <etaern@yahoo.com>:

[#345893] Re: Executing system commands in threads under Ruby 1.8.6 — vhaerun vh <etaern@...> 2009/09/07

Here's a link to the question I asked on SO:

[#345901] Re: Executing system commands in threads under Ruby 1.8.6 — Eleanor McHugh <eleanor@...> 2009/09/07

On 7 Sep 2009, at 09:55, vhaerun vh wrote:

[#345904] Re: Executing system commands in threads under Ruby 1.8.6 — Bertram Scharpf <lists@...> 2009/09/07

Hi,

[#345886] Ruby 1.9, Rubygems, and .gemspec warnings — Rob Sanheim <rsanheim@...>

Hi all

14 messages 2009/09/07

[#346018] Tutorial challenge program help — Chris Logan <t-logan3@...>

Hello all im really new to ruby as in a few days and getting into it. i

20 messages 2009/09/09
[#346023] Re: Tutorial challenge program help — 7stud -- <bbxx789_05ss@...> 2009/09/09

Chris Logan wrote:

[#346027] Re: Tutorial challenge program help — Chris Logan <t-logan3@...> 2009/09/09

7stud -- wrote:

[#346091] How Are Variables Kept Independent of Each Other Yet Pass Values? — Mason Kelsey <masonkelsey@...>

Somewhere in the several books I've been learning Ruby from there was the

14 messages 2009/09/10
[#346096] Re: How Are Variables Kept Independent of Each Other Yet Pass Values? — venkatesh Peddi <venkat.peddi@...> 2009/09/10

[#346106] Asynchronous http POST? — Ivan Shevanski <ocelot117@...>

Hey everyone, I'm new to Ruby and to the mailing list, so go easy.

14 messages 2009/09/10
[#346166] Re: Asynchronous http POST? — Ezra Zygmuntowicz <ezmobius@...> 2009/09/10

[#346193] populating a hash from an array using inject — Glenn Jackman <glennj@...>

I was looking at this problem on Stack Overflow (this one:

12 messages 2009/09/10

[#346324] module to overwrite method defined via define_method — Gaspard Bucher <gaspard@...>

Hi List !

17 messages 2009/09/13
[#346326] Re: module to overwrite method defined via define_method — "David A. Black" <dblack@...> 2009/09/13

Hi --

[#346328] Re: module to overwrite method defined via define_method — Gaspard Bucher <gaspard@...> 2009/09/13

David A. Black wrote:

[#346347] FasterCSV.foreach loop — Dot Baiki <dot_baiki@...>

Hello community,

16 messages 2009/09/13

[#346367] .map.with_object(3){|v|v+3} #=> 3 Is this a bug? — ErMaker <ermaker@...>

At ruby 1.9.2dev (2009-07-18 trunk 24186) [i386-mswin32_90]

15 messages 2009/09/14

[#346383] Pre-allocate large amount of memory? — Carsten Gehling <carsten@...>

I've created a small daemon, that serves certain data very fast to our

15 messages 2009/09/14
[#346404] Re: Pre-allocate large amount of memory? — Robert Klemme <shortcutter@...> 2009/09/14

2009/9/14 Carsten Gehling <carsten@sarum.dk>:

[#346419] whats the best way to package deploy a Ruby app to windows??? (no UI, also standalone if possible) — Greg Hauptmann <greg.hauptmann.ruby@...>

Hi,

8 messages 2009/09/14

[#346452] Command line — Rong <ron.green@...>

Please forgive this stupid newb question but I thought it was possible

13 messages 2009/09/15

[#346500] Array of Hashes in an array of hashes - Complicated! — Matt Brooks <mattbrooks@...>

I have an unique problem that I can't solve. I am sorry this is long,

17 messages 2009/09/15
[#346505] Re: Array of Hashes in an array of hashes - Complicated! — John W Higgins <wishdev@...> 2009/09/15

Morning Matt,

[#346508] Re: Array of Hashes in an array of hashes - Complicated! — Matt Brooks <mattbrooks@...> 2009/09/15

Hi John,

[#346510] Re: Array of Hashes in an array of hashes - Complicated! — John W Higgins <wishdev@...> 2009/09/15

Matt,

[#346515] Re: Array of Hashes in an array of hashes - Complicated! — Aldric Giacomoni <aldric@...> 2009/09/15

+1 on object creation

[#346574] string to array — Re BR <rereis@...>

Hello all,

15 messages 2009/09/16

[#346611] block issues... — Dylan Lukes <revenantphoenix@...>

In the following block, each plugin in the constant hash PLUGINS is

17 messages 2009/09/16

[#346621] Monkey Patching 2 Methods, Overrides One Method, Not The Other — MaggotChild <hsomob1999@...>

I'm monkey patching 2 methods of an existing module: some_method() and

18 messages 2009/09/17

[#346645] Mucking about with dynamically adding methods to objects — Paul Smith <paul@...>

I've been toying with Ruby for a while, but only now am I beginning to

12 messages 2009/09/17
[#346652] Re: Mucking about with dynamically adding methods to objects — Jes俍 Gabriel y Gal疣 <jgabrielygalan@...> 2009/09/17

On Thu, Sep 17, 2009 at 11:44 AM, Paul Smith <paul@pollyandpaul.co.uk> wrote:

[#346665] Re: Mucking about with dynamically adding methods to objects — Paul Smith <paul@...> 2009/09/17

2009/9/17 Jes俍 Gabriel y Gal疣 <jgabrielygalan@gmail.com>:

[#346676] Value isn't appended in puts statement(appears on next line) — Mrmaster Mrmaster <mrsolarlife@...>

Hello,

13 messages 2009/09/17
[#346678] Re: Value isn't appended in puts statement(appears on next line) — Jes俍 Gabriel y Gal疣 <jgabrielygalan@...> 2009/09/17

On Thu, Sep 17, 2009 at 8:51 PM, Mrmaster Mrmaster

[#346759] Newbie: Are Ruby regexp's a subset, superset, or equal to Perl's? — Harry <simonsharry@...>

Hi,

13 messages 2009/09/18

[#346774] Exceptional Rails Developer — Richard Price <richard.price100@...>

Hi all,

32 messages 2009/09/18
[#347451] Re: Exceptional Rails Developer — Ilan Berci <ilan.berci@...> 2009/09/30

Richard Price wrote:

[#347452] Re: Exceptional Rails Developer — Zundra Daniel <zundra.daniel@...> 2009/09/30

At least he didn't say "Rockstar" or "Ninja"

[#347476] Re: Exceptional Rails Developer — David Masover <ninja@...> 2009/09/30

On Wednesday 30 September 2009 01:45:27 pm Zundra Daniel wrote:

[#347477] Re: Exceptional Rails Developer — Greg Donald <gdonald@...> 2009/09/30

On Wed, Sep 30, 2009 at 6:44 PM, David Masover <ninja@slaphack.com> wrote:

[#347482] Re: Exceptional Rails Developer — David Masover <ninja@...> 2009/10/01

On Wednesday 30 September 2009 06:54:16 pm Greg Donald wrote:

[#347514] Re: Exceptional Rails Developer — Eleanor McHugh <eleanor@...> 2009/10/01

On 1 Oct 2009, at 01:32, David Masover wrote:

[#347551] Re: Exceptional Rails Developer — David Masover <ninja@...> 2009/10/01

On Thursday 01 October 2009 08:20:26 am Eleanor McHugh wrote:

[#347592] Re: Exceptional Rails Developer — Eleanor McHugh <eleanor@...> 2009/10/02

On 1 Oct 2009, at 19:15, David Masover wrote:

[#347596] Re: Exceptional Rails Developer — Aldric Giacomoni <aldric@...> 2009/10/02

[#346775] Determining if a file is binary or text — James Masters <james.d.masters@...>

Hi all,

15 messages 2009/09/18

[#346891] Incrementing variable names in a loop? — Matt Brooks <mattbrooks@...>

I have a function write_log that takes in a string and it prints to

10 messages 2009/09/21

[#347044] the great ruby editor and ide roundup — Martin DeMello <martindemello@...>

https://spreadsheets.google.com/ccc?key=0Al_hzYODcgxwdG9tUFhqcVVoUDVaLTlqT2YtNjV1N0E&hl=en

26 messages 2009/09/23
[#347045] Re: the great ruby editor and ide roundup — Rajinder Yadav <devguy.ca@...> 2009/09/23

On Wed, Sep 23, 2009 at 4:02 PM, Martin DeMello <martindemello@gmail.com> wrote:

[#347058] How do you limit the line length of the output commands? Where is pqueue library documented? — Mason Kelsey <masonkelsey@...>

There must be an easy way to solve the problem of controlling the length of

12 messages 2009/09/23

[#347156] Roulette & rand — Semih Ozkoseoglu <ozansemih@...>

Hi,

22 messages 2009/09/25
[#347161] Re: Roulette & rand — Stefano Crocco <stefano.crocco@...> 2009/09/25

On Friday 25 September 2009, Semih Ozkoseoglu wrote:

[#347164] Re: Roulette & rand — Semih Ozkoseoglu <ozansemih@...> 2009/09/25

Hi again Stefano,

[#347171] Re: Roulette & rand — Stefano Crocco <stefano.crocco@...> 2009/09/25

On Friday 25 September 2009, Semih Ozkoseoglu wrote:

[#347173] Re: Roulette & rand — Semih Ozkoseoglu <ozansemih@...> 2009/09/25

Stefano, Paul,

[#347179] Re: Roulette & rand — Semih Ozkoseoglu <ozansemih@...> 2009/09/25

Hi again,

[#347193] How to remove duplicate elements in a 2D array — Li Chen <chen_li3@...>

Hi all,

20 messages 2009/09/25

[#347202] Backporting Enumerator.new { ... } to Ruby 1.8.7 — "Shot (Piotr Szotkowski)" <shot@...>

Hello, good people of ruby-talk.

12 messages 2009/09/25

[#347260] handling of regexp objects that aren't referenced by variables, arrays, tables or objects — ThomasW <x.zupftom@...>

Hi,

12 messages 2009/09/27

[#347354] How do I use nitpick — "Michael W. Ryder" <_mwryder@...>

I was looking for a program like lint in C and came across nitpick. I

23 messages 2009/09/29
[#347366] Re: How do I use nitpick — Hassan Schroeder <hassan.schroeder@...> 2009/09/29

On Mon, Sep 28, 2009 at 9:25 PM, Michael W. Ryder

[#347397] Re: How do I use nitpick — "Michael W. Ryder" <_mwryder@...> 2009/09/29

Hassan Schroeder wrote:

[#347398] Re: How do I use nitpick — Ryan Davis <ryand-ruby@...> 2009/09/29

[#347364] Group by unique entries of a hash — Ne Scripter <stuart.clarke@...>

I have two data sets loaded into a hash to give the following output

15 messages 2009/09/29

[#347443] Get current working copy version in subversion/git — Anthony Metcalf <anthony.metcalf@...>

Hi,

11 messages 2009/09/30

[#347456] SystemStackError: stack level too deep > how make it deeper? — Joshua Muheim <forum@...>

Hi all

15 messages 2009/09/30
[#347459] Re: SystemStackError: stack level too deep > how make it deeper? — Jason Roelofs <jameskilton@...> 2009/09/30

On Wed, Sep 30, 2009 at 3:47 PM, Joshua Muheim <forum@josh.ch> wrote:

Re: Roulette & rand

From: Stefano Crocco <stefano.crocco@...>
Date: 2009-09-25 06:34:32 UTC
List: ruby-talk #347161
On Friday 25 September 2009, Semih Ozkoseoglu wrote:
> |Hi,
> |
> |I'm trying to teach my self ruby so i decided to write a simple roulette
> |that picks a rand number (0 to 36) then decides if its red or black. but
> |after i've written a version of the code i realized that the code was
> |biased towards black ( much easier to see over 1 million rolls)
> |
> |Then to test this I've simplified everything and its still biased
> |against black. if i take 0 out of the equation and made use (1+rand(25))
> |the bias disappeared.
> |
> |Anyway without further annoying you here is the code. If you spin it for
> |over a million you can easily see the bias (i tried up to 1000000000).
> |
> |Thanks for any help. I know it's not a life or death situation but for
> |the life of me I just want to know why is this happening.
> |
> |THE CODE:
> |
> |# ARRAYS =======================
> |
> |black = [2, 4, 6, 8, 10, 11, 13, 15, 17, 20, 22, 24, 26, 28, 29, 31, 33,
> |35]
> |red = [1, 3, 5, 7, 9, 12, 14, 16, 18, 19, 21, 23, 25, 27, 30, 32, 34,
> |36]
> |zero = [0]
> |
> |# VARIABLES ===================
> |
> |bl = 0
> |rd = 0
> |zr = 0
> |
> |# # OF ROLLS ==================
> |
> |puts 'How many rolls to simulate'
> |number_of_rolls = gets.chomp.to_i
> |
> |# THE LOOP ====================
> |
> |while number_of_rolls > 0
> |
> |
> |  number = rand(36)
> |
> |  if
> |    black.include?(number)
> |    bl +=1
> |  elsif
> |    red.include?(number)
> |    rd +=1
> |  elsif
> |    zero.include?(number)
> |    zr +=1
> |  end
> |  number_of_rolls -=1
> |end
> |
> |puts bl
> |puts rd
> |puts zr

I think the problem comes from the fact that rand(n) returns an integer 
between 0 and n-1. In your case, this means that the number 36 will never be 
generated, which in turn implies that there are more black numbers (18) than 
red (17 since 36 will never be generated). To avoid this, you'll need to 
replace rand(36) with rand(37), which generates numbers between 0 and 36. By 
the way, you can greatly simplify your code, like this:

colors = {}

[2, 4, 6, 8, 10, 11, 13, 15, 17, 20, 22, 24, 26, 28, 29, 31,33,35].each do |i| 
  colors[i] = :black
end
[1, 3, 5, 7, 9, 12, 14, 16, 18, 19, 21, 23, 25, 27, 30, 32,34,36].each do |i|
  colors[i] = :red
end
colors[0] = :zero

results = {:black => 0, :red => 0, :zero => 0}

puts 'How many rolls to simulate'
number_of_rolls = gets.chomp.to_i

number_of_rolls.times do
  number = rand(37)
  color = colors[number]
  results[color] += 1
end

puts "Black: #{results[:black]}"
puts "Red: #{results[:red]}"
puts "Zero: #{results[:zero]}"

What this code does is the following:
* create a hash (called colors) which associates each number with its color, 
represented by a symbol. The hash is filled from arrays containing the black 
numbers and the red ones (it could also be filled by hand:
  colors[1] = :red
  colors[2] = :black
  ...
* create the hash results which will contain the number of times each color is 
choosen. Therefore, the hash contains three entries, :black, :red and :zero, 
all set to 0
* let the user choose the number of rolls
* for the number of times chosen by the user, do the following
 - generate a random number between 0 and 36
 - get the color corresponding to the number. This is done by looking at the 
value corresponding to the number in the colors hash
 - increase by one the result relative to the chosen color
* displays the result

I hope this helps

Stefano

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