Biased randomness with probability weights vector

biased_randomness.rb

# Work in progress 
# 
# This function generates the vector
#
# examples: 
#   [3, 2, 2, 1]
#   [5, 4, 4, 3, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1]
def probability_weights_vector(n)
  n.downto(1).reduce([]) { |ary, i| 
    ary.push(*([i] * (n -i + 1)))
  }
end

# get the vector
v = probability_weights_vector(5)

# calculate the vector length
v_range = (0..v.size-1)

# this is where we will put 
# the summary
summary ||= {}
  
# Run throught the loop for 1000 times
# and keep track of the distribution
1000.times {
  returned = v[rand(r_param)]
  
  summary["returned_#{returned}"] ||= 0
  summary["returned_#{returned}"]  += 1
}

# OK, print out the results
# and see the distribution
p res.sort