gamma.clj

(ns various-distributions.gamma
  (:require [incanter.charts :as c]
            [incanter.core :as i]
            [incanter.distributions :as d]
            [incanter.stats :as s]))

;; https://github.com/incanter/incanter/issues/245
(defn show-gamma-distribution []
  (let [dist (d/gamma-distribution 2 2)
        n 100000
        x (repeatedly n #(d/draw dist))
        pdf-fn #(d/pdf dist %)]
    (let [nbins 50
          series-label "gamma"
          [x-min x-max] (s/quantile x :probs [0.01 0.99])]
      (-> (c/histogram x :nbins nbins :density true :series-label series-label)
          (c/set-x-range x-min x-max)
          (c/add-function pdf-fn x-min x-max :series-label series-label)
          i/view))))