CODEWITHSUNDEEP
ruby
Gibson
Gibson

Reputation: 2085

Predict winning number depending on results?

I want to generate the most probable number depending on the latest lottery results I have on a CSV.

I have this script:

h = Hash.new
f = File.open('numbers.csv', "r")
f.each_line { |line|
  numbers = line.split
  numbers.each { |w|
    if h.has_key?(w)
      h[w] = h[w] + 1
    else
      h[w] = 1
    end
  }
}

# sorteamos el hash por valor, y lo pintamos según la concurrencia
h.sort{|a,b| a[1]<=>b[1]}.each { |elem|
  puts "\"#{elem[0]}\" tiene #{elem[1]} concurrencia"
}

That will tell me which numbers have the most ocurrencies. I want to "sample" a number depending on these results that has the most probability.

How can I achieve this? Thanks!

Upvotes: 0

Views: 78

Answers (1)

Max
Max

Reputation: 22375

I don't think Ruby has a built-in elegant way of doing this. You can treat your hash as a bunch of bins, where the number of occurrences of each number is the bin size. Then you can calculate the total bin width, get a random sample, and iterate to find out which bin the sample lands in.

def weighted_sample h
  weight = h.values.reduce(:+)
  sample = rand weight
  h.each do |n, w|
    return n if sample < w
    sample -= w
  end
end

Array.new(10) { weighted_sample({1 => 8, 2 => 4, 3 => 2}) }
# [2, 2, 1, 1, 1, 3, 1, 1, 1, 1]

Tip: there's a much nicer way to build that hash

h = Hash.new 0
# ...
h[w] += 1

Upvotes: 2

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