Data commit

Task/Statistics-Basic/CoffeeScript/statistics-basic.coffee

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+generate_statistics = (n) ->
+  hist = {}
+
+  update_hist = (r) ->
+    hist[Math.floor 10*r] ||= 0
+    hist[Math.floor 10*r] += 1
+
+  sum = 0
+  sum_squares = 0.0
+
+  for i in [1..n]
+    r = Math.random()
+    sum += r
+    sum_squares += r*r
+    update_hist r
+  mean = sum / n
+  stddev = Math.sqrt((sum_squares / n) - mean*mean)
+
+  [n, mean, stddev, hist]
+
+display_statistics = (n, mean, stddev, hist) ->
+  console.log "-- Stats for sample size #{n}"
+  console.log "mean: #{mean}"
+  console.log "sdev: #{stddev}"
+  for x, cnt of hist
+    bars = repeat "=", Math.floor(cnt*300/n)
+    console.log "#{x/10}: #{bars} #{cnt}"
+
+repeat = (c, n) ->
+  s = ''
+  s += c for i in [1..n]
+  s
+
+for n in [100, 1000, 10000, 1000000]
+  [n, mean, stddev, hist] = generate_statistics n
+  display_statistics n, mean, stddev, hist