Add Preprocess module

lib/uplot/command.rb

@@ -3,6 +3,72 @@ require 'csv'
 require 'unicode_plot'
 
 module Uplot
+  Data = Struct.new(:headers, :series)
+
+  module Preprocess
+    module_function
+
+    def input(input, delimiter, headers, transpose)
+      arr = read_csv(input, delimiter)
+      headers = get_headers(arr, headers, transpose)
+      series = get_series(arr, headers, transpose)
+      Data.new(headers, series)
+    end
+
+    def read_csv(input, delimiter)
+      CSV.parse(input, col_sep: delimiter)
+         .delete_if do |i|
+           i == [] or i.all? nil
+         end
+    end
+
+    # Transpose different sized ruby arrays
+    # https://stackoverflow.com/q/26016632
+    def transpose2(arr)
+      Array.new(arr.map(&:length).max) { |i| arr.map { |e| e[i] } }
+    end
+
+    def get_headers(arr, headers, transpose)
+      if headers
+        if transpose
+          arr.map(&:first)
+        else
+          arr[0]
+        end
+      end
+    end
+
+    def get_series(arr, headers, transpose)
+      if transpose
+        if headers
+          arr.map { |row| row[1..-1] }
+        else
+          arr
+        end
+      else
+        if headers
+          transpose2(arr[1..-1])
+        else
+          transpose2(arr)
+        end
+      end
+    end
+
+    def count(arr)
+      # tally was added in Ruby 2.7
+      if Enumerable.method_defined? :tally
+        arr.tally
+      else
+        # https://github.com/marcandre/backports
+        arr.each_with_object(Hash.new(0)) { |item, res| res[item] += 1 }
+           .tap { |h| h.default = nil }
+      end
+        .sort { |a, b| a[1] <=> b[1] }
+        .reverse
+        .transpose
+    end
+  end
+
   class Command
     Params = Struct.new(
       :title,