require 'daru'
Daru.plotting_library = :gruff

df = Daru::DataFrame.new({
  a: [1, 3, 5, 7, 5, 0],
  b: [1, 5, 2, 5, 1, 0],
  c: [1, 6, 7, 2, 6, 0]
  }, index: 'a'..'f')
df.plot type: :line

df.plot type: :line, x: :a, y: [:b, :c]

df.plot type: :scatter, x: :a, y: :b

df.plot type: :bar

df = Daru::DataFrame.new({
  a: [1, 2, 3, 4, 5],
  b: [3, 2, 5, 1, 5],
  c: [:a, :a, :a, :b, :b]
  })
df.to_category :c

df.plot type: :scatter, x: :a, y: :b, categorized: {by: :c}