lib/dimsum.rb in dimsum-0.0.1 vs lib/dimsum.rb in dimsum-0.0.2

@@ -1,5 +1,38 @@
 require "dimsum/version"
 
 module Dimsum
-  # Your code goes here...
+  def reservoir_file(filename, sample_size)
+    random = Random.new
+    out = []
+
+    File.open(filename, "r").each_line.each_with_index do |line, line_number|
+      keep, index = keep_line_in_index(line_number, sample_size, random)
+      out[index] = line if keep
+    end
+    out
+  end
+
+  def reservoir_stdin(sample_size)
+    random = Random.new
+    input_line_number = 0
+    out = []
+
+    STDIN.readlines.each do |line|
+      keep, index = keep_line_in_index(input_line_number, sample_size,  random)
+      out[index] = line if keep
+      input_line_number += 1
+    end
+
+    out
+  end
+
+  def keep_line_in_index(input_line_number, sample_size, random_number_generator)
+    if input_line_number <= sample_size
+      [true, input_line_number]
+    else
+      r = random_number_generator.rand(0 .. input_line_number)
+      keep = r < sample_size 
+      [keep, r]
+    end
+  end
 end