fix addition for hashes with 2d keys

lib/chartnado/series/wrap.rb

@@ -44,7 +44,7 @@ def add(*series, scalar_sum: 0.0)
         (series, scalars) = [__getobj__, *series].partition { |s| s.respond_to?(:map) }
         scalar_sum += scalars.reduce(:+) || 0.0
 
-        if wrap(series.first).dimensions == 3
+        if has_separate_named_series?
           result = series.map(&:to_a).flatten(1).group_by(&:first).map do |name, values|
             data = values.map(&:second).reduce(Hash.new(scalar_sum)) do |hash, values|
               values.each do |key, value|
@@ -77,8 +77,8 @@ def over(bottom, multiplier: 1.0, precision: 2)
 
         if dimensions > bottom.dimensions
           top_series_by_name = data_by_name
-          if hash_of_named_series? || array_of_named_series?
-            top_series_by_name.map do |name, top_values|
+          if has_separate_named_series?
+            data_by_name.map do |name, top_values|
               [
                 name,
                 wrap(top_values).
@@ -185,6 +185,10 @@ def with_precision(precision, value)
       def wrap(val)
         self.class[val]
       end
+
+      def has_separate_named_series?
+        hash_of_named_series? || array_of_named_series?
+      end
     end
   end
 end

spec/series_spec.rb

@@ -71,6 +71,11 @@ class << self
         expect(series_sum(2,{'a' => {0 => 3}})).to eq ([['a', {0 => 5}]])
       end
     end
+    describe "adding a scalar to a hash with 2 dimensional keys" do
+      it "returns each item of the array with a scalar added" do
+        expect(series_sum({['a', 0] => 3}, 1)).to eq ({['a', 0] => 4})
+      end
+    end
     describe "adding two hashes" do
       it "returns each item of the array with a scalar added" do
         expect(series_sum({0 => 1},{0 => 2})).to eq ({0 => 3})