diff --git a/lib/youplot/backends/processing.rb b/lib/youplot/backends/processing.rb
deleted file mode 100644
index eb5aea3..0000000
--- a/lib/youplot/backends/processing.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require 'enumerable/statistics'
-
-module YouPlot
-  # plotting functions.
-  module Backends
-    module Processing
-      module_function
-
-      def count_values(arr, tally: true)
-        a = arr.value_counts
-        [a.keys, a.values]
-      end
-    end
-  end
-end
diff --git a/lib/youplot/backends/unicode_plot_backend.rb b/lib/youplot/backends/unicode_plot_backend.rb
index 95a34e9..53bc9b2 100644
--- a/lib/youplot/backends/unicode_plot_backend.rb
+++ b/lib/youplot/backends/unicode_plot_backend.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require_relative 'processing'
 require 'unicode_plot'
 
 module YouPlot
@@ -16,7 +15,7 @@ module YouPlot
         series = data.series
         # `uplot count`
         if count
-          series = Processing.count_values(series[0])
+          series = series[0].value_counts.yield_self { |h| [h.keys, h.values] }
           params.title = headers[0] if headers
         end
         if series.size == 1
diff --git a/test/youplot/backends/processing_test.rb b/test/youplot/backends/processing_test.rb
deleted file mode 100644
index 88954b5..0000000
--- a/test/youplot/backends/processing_test.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require_relative '../../test_helper'
-
-class YouPlotCommandTest < Test::Unit::TestCase
-  test :count_values do
-    @m = YouPlot::Backends::Processing
-    assert_equal([%i[a b c], [3, 2, 1]], @m.count_values(%i[a a a b b c]))
-    assert_equal([%i[c b a], [3, 2, 1]], @m.count_values(%i[a b b c c c]))
-  end
-
-  test :count_values_non_tally do
-    @m = YouPlot::Backends::Processing
-    assert_equal([%i[a b c], [3, 2, 1]], @m.count_values(%i[a a a b b c], tally: false))
-    assert_equal([%i[c b a], [3, 2, 1]], @m.count_values(%i[a b b c c c], tally: false))
-  end
-end