Time for an 2014 update…

Task/Stem-and-leaf-plot/Ruby/stem-and-leaf-plot-2.rb

@@ -0,0 +1,29 @@
+class StemLeafPlot
+  def initialize(data, leaf_digits=1)
+    @leaf_digits = leaf_digits
+    multiplier = 10 ** @leaf_digits
+    @plot = data.sort.group_by{|x| x / multiplier}
+    @plot.default = []
+    @plot.each{|k,v| @plot[k] = v.map{|val| val % multiplier}}
+  end
+
+  def print
+    min, max = @plot.keys.minmax
+    stem_width = max.to_s.size
+    (min..max).each do |stem|
+      leaves = @plot[stem].inject("") {|str,leaf| str << "%0*d " % [@leaf_digits, leaf]}
+      puts "%*s | %s" % [stem_width, stem, leaves]
+    end
+  end
+end
+
+data = DATA.read.split.map {|s| Integer(s)}
+StemLeafPlot.new(data).print
+
+__END__
+12 127 28 42 39 113 42 18 44 118 44 37 113 124 37 48 127 36 29 31 125 139 131
+115 105 132 104 123 35 113 122 42 117 119 58 109 23 105 63 27 44 105 99 41 128
+121 116 125 32 61 37 127 29 113 121 58 114 126 53 114 96 25 109 7 31 141 46 13
+27 43 117 116 27 7 68 40 31 115 124 42 128 52 71 118 117 38 27 106 33 117 116
+111 40 119 47 105 57 122 109 124 115 43 120 43 27 27 18 28 48 125 107 114 34
+133 45 120 30 127 31 116 146