I’m trying to generate 8 unique random numbers between 1 and 13.
for example my first set of results could be:
2, 8, 4, 6, 3, 10, 12, 1
the results need to be between 1 and 13 and they must be unique.
The rand(12) + 1 returns random numbers between 1 and 13, but they are
not unique. Any quick solutions?
Jimmy P. wrote:
I’m trying to generate 8 unique random numbers between 1 and 13.
for example my first set of results could be:
2, 8, 4, 6, 3, 10, 12, 1
the results need to be between 1 and 13 and they must be unique.
The rand(12) + 1 returns random numbers between 1 and 13, but they are
not unique. Any quick solutions?
~$ irb
irb(main):001:0> (1…13).to_a.sort_by{rand}[0…7]
=> [7, 3, 8, 2, 11, 4, 1, 9]
irb(main):002:0>
ar = []
while ar.length < 8
ar << rand(12) + 1
ar.uniq!
end
/Shawn
On Mon, Mar 24, 2008 at 6:00 PM, Jimmy P. [email protected]
On Mar 24, 7:00 pm, Jimmy P. [email protected] wrote:
–
Posted viahttp://www.ruby-forum.com/.
Here’s one more possibility:
numbers = (1…13).to_a
randoms = []
8.times {randoms << numbers.delete_at(rand(numbers.size))}
Though, Tim’s solution might be most readable.
Chris
On Tue, Mar 25, 2008 at 10:26 AM, Tim H. [email protected]
wrote:
Jimmy P. wrote:
Tim H. wrote:
~$ irb
irb(main):001:0> (1…13).to_a.sort_by{rand}[0…7]
=> [7, 3, 8, 2, 11, 4, 1, 9]
irb(main):002:0>
thanks Tim. i like it.
You’re welcome. Turns out you don’t need the to_a. One less method.
(1…13).sort_by{ rand }.first(7)
my attempt to improve upon it
Jimmy P. wrote:
Tim H. wrote:
~$ irb
irb(main):001:0> (1…13).to_a.sort_by{rand}[0…7]
=> [7, 3, 8, 2, 11, 4, 1, 9]
irb(main):002:0>
thanks Tim. i like it.
You’re welcome. Turns out you don’t need the to_a. One less method.
From: Michael F. [mailto:[email protected]]
(1…13).sort_by{ rand }.first(7)
careful, Mike ^^^^^^^^
On Mon, Mar 24, 2008 at 9:08 PM, Michael F.
[email protected] wrote:
You’re welcome. Turns out you don’t need the to_a. One less method.
(1…13).sort_by{ rand }.first(7)
my attempt to improve upon it
Tim’s shuffle and cut technique seems fishy to me at first, but I like
it. Now I’ll be up nights reading my old probability texts
Todd
On Tue, Mar 25, 2008 at 10:24:54AM +0900, Chris S. wrote:
not unique. Any quick solutions?
Posted viahttp://www.ruby-forum.com/.
Here’s one more possibility:
numbers = (1…13).to_a
randoms = []
8.times {randoms << numbers.delete_at(rand(numbers.size))}
Though, Tim’s solution might be most readable.
You might also look through the solutions for Ruby Q. #39 (Sampling).
http://rubyquiz.com/quiz39.html
there are couple of other ruby quizes where things like this are touched
on.
You might browse through the archives.
enjoy,
-jeremy
On Tue, Mar 25, 2008 at 11:26 AM, Peña, Botp [email protected]
wrote:
From: Michael F. [mailto:[email protected]]
(1…13).sort_by{ rand }.first(7)
careful, Mike ^^^^^^^^
oh, i meant .first(8) ^^;
^ manveru
On Tue, Mar 25, 2008 at 6:54 AM, Subbu [email protected]
wrote:
RMagick 2:http://rmagick.rubyforge.org/rmagick2.html
Hey Tim, I am a bit lost here sort_by accepts a block. But I see
you are just passing it a method.
Look again
Robert
–
http://ruby-smalltalk.blogspot.com/
Whereof one cannot speak, thereof one must be silent.
Ludwig Wittgenstein
On Mar 24, 6:05 pm, Tim H. [email protected] wrote:
not unique. Any quick solutions?
~$ irb
irb(main):001:0> (1…13).to_a.sort_by{rand}[0…7]
=> [7, 3, 8, 2, 11, 4, 1, 9]
irb(main):002:0>
–
RMagick:http://rmagick.rubyforge.org/
RMagick 2:http://rmagick.rubyforge.org/rmagick2.html
Hey Tim, I am a bit lost here sort_by accepts a block. But I see
you are just passing it a method. How does this work? Does Ruby
convert the return value of the method to a block and then sorts it?
Do you mind explaining it for me? Thanks so much.
Tim H. wrote:
Jimmy P. wrote:
I’m trying to generate 8 unique random numbers …
the results need to be between 1 and 13
and they must be unique.
~$ irb
irb(main):001:0> (1…13).to_a.sort_by{rand}[0…7]
=> [7, 3, 8, 2, 11, 4, 1, 9]
For anyone still counting :), the following builds on Tim’s approach:
(1…13).to_a.shuffle.first(8)
Array#shuffle is only available in ruby 1.9+ though.
Cheers, lasitha
Jimmy P. wrote:
I’m trying to generate 8 unique random numbers between 1 and 13.
for example my first set of results could be:
2, 8, 4, 6, 3, 10, 12, 1
the results need to be between 1 and 13 and they must be unique.
The rand(12) + 1 returns random numbers between 1 and 13, but they are
not unique. Any quick solutions?
http://realrand.rubyforge.org/