How do I generate a list of n unique random numbers in Ruby? I am trying to create a randomly generated array of x numbers with no duplicates. I am choosing numbers, one at a time, then comparing each new number to the numbers already in the array. 

Here is my code. At the end I should have an array of seven numbers, none that match, but sometimes I get a nil:

array = [] #DEFINES THE ARRAY

array[0] = rand(10)  #THIS CHOOSES FIRST NUMBER (FN) AND PUTS IT IN THE FIRST ARRAY SPOT
p "fn = #{array[0]}"

for i in 1..6  #START OF FOR LOOP TO GET 6 NUMBERS IN THE ARRAY - WHY 6?  THE FIRST NUMBER THAT POPPED IN MY HEAD

  p "Iteration #{i} -------------------------"  # THIS IS JUST SO I KNOW WHERE I AM IN THE LOOPS

  @x = rand(10)  #THIS CHOOSES THE NEXT NUMBER AND ALL NUMBERS AFTER

  array.each do |uc|  # THIS IS THE LOOP THAT COMPARES ALL NUMBERS

    @type = @x == uc ? "yes" : "no"  #DOES THE CHOSEN NUMBER EQUAL ANY NUMBER IN THE ARRAY

    p "does #{uc} = #{@x}? #{@type}"
    if @type == "yes"  # IF THE COMPARE IS TRUE, I DON'T WANT ANYTHING DONE.  IT WILL CYCLE THRU AND GET A NEW NUMBER

      i = 1 
      p "YES #{@x} = #{uc}"
      break
    end  #END OF IF YES
  end  #END OF ARRAY EACH

  if @type == "no"  #IF NO, PUT NEXT NUMBER (@X) INTO THE NEXT ARRAY SPOT.

    p "in last if type= #{@type}"  #THESE STATEMENTS JUST PRINT OUT THE DIFFERENT VARIABLES SO I KNOW I AM GETTING WHAT I EXPECT

    p "in last if x = #{@x}"
    p "in last if i = #{i}"
    @x = array[i]  #THIS "SHOULD" FILL THE NEXT ARRAY SPOT - BUT DOESN'T SEEM TO

    p "#{array[i]} is in the array"  #THIS PRINT OUT IS BLANK - STATEMENT ABOVE DID NOT WORK.

    p array[i]
  end  #END OF IF NO

end  #END OF FOR LOOP

p array #PRINTS OUT THE CONTENTS OF THE ARRAY


I know there are probably quicker and easier ways to do this, but I am starting out with what I know, and building up.
The sample method does what you want: 

(1..10).to_a.sample(7) #=&gt; [2, 9, 1, 6, 8, 10, 4]