Try to improve transpose

lib/uplot/command.rb

@@ -93,16 +93,25 @@ module Uplot
       end
     end
 
+    # Note: How can I transpose different sized ruby arrays?
+    # https://stackoverflow.com/questions/26016632/how-can-i-transpose-different-sized-ruby-arrays
+    def transpose2(arr) # Should be renamed
+      arr[0].zip(*arr[1..-1])
+    end
+
     def preprocess(input)
       data = CSV.parse(input, col_sep: @delimiter)
+      headers = nil
+      if @transpose
         if @headers
-        headers = data.shift
+          headers = []
-        data = data.transpose unless @transpose
+          data.each { |series| headers << series.shift } # each but destructive like map
-        [data, headers]
-      else
-        data = data.transpose unless @transpose
-        [data, nil]
         end
+      else
+        headers = data.shift if @headers
+        data = transpose2(data)
+      end
+      [data, headers]
     end
 
     def barplot(data, headers)