Number of blades on a safety razor, over time

blades.clj

(ns blades
  (:use [incanter core stats charts])
  (:import java.text.SimpleDateFormat))

(def dates
  {"first one-bladed gilette safety razor, 1" 1888
   "Trac II" 1971
   "Mach3" 1998
   "Wilkinson Quattro" 2003
   "Fusion" 2006
   "Albert Heijn" 2011}) ; http://en.wikipedia.org/wiki/Safety_razor

(defn parse-year [year]
  (.getTime
    (.parse (SimpleDateFormat. "yyyy") (str year))))

(-> (time-series-plot
      (map parse-year (vals dates)) 
      (range 1 (inc (count dates)))
      :x-label "t"
      :y-label "number of blades")
  view)