DataFrame#vectors= should change the name of the vectors in @data. (#…

…293)

* create test

* DataFrame#vector= changes the name of vectors in @DaTa

lib/daru/dataframe.rb

@@ -1356,6 +1356,9 @@ def vectors= new_index
       end
 
       @vectors = new_index
+      @data.zip(new_index.to_a).each do |vect, name|
+        vect.name = name
+      end
       self
     end
 

spec/dataframe_spec.rb

@@ -2594,6 +2594,13 @@
         @df.vectors = Daru::Index.new([1,2,'3',4,'5'])
       }.to raise_error(ArgumentError)
     end
+
+    it "change name of vectors in @data" do
+      new_index_array = [:k, :l, :m]
+      @df.vectors = Daru::Index.new(new_index_array)
+
+      expect(@df.data.map { |vector| vector.name }).to eq(new_index_array)
+    end
   end
 
   context "#rename_vectors" do