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Task/Statistics-Basic/Nim/statistics-basic.nim

@@ -0,0 +1,32 @@
+import math, strutils
+randomize()
+
+proc sd(ns): auto =
+  var sx, sxx = 0.0
+  for x in ns:
+    sx += x
+    sxx += x * x
+  let sd = if ns.len > 0: sqrt(float(ns.len) * sxx - sx * sx) / float(ns.len)
+           else: 0
+  (sd, sx / float(ns.len))
+
+proc histogram(ns) =
+  var h = newSeq[int](10)
+  for n in ns:
+    let pos = int(n * 10)
+    inc h[pos]
+
+  const maxWidth = 50
+  let mx = max(h)
+  echo ""
+  for n, i in h:
+    echo n/10,": ",repeatChar(int(i / mx * maxWidth), '+')
+  echo ""
+
+for i in [10, 100, 1_000, 10_000, 100_000]:
+  var n = newSeq[float](i)
+  for x in 0..n.high: n[x] = random(1.0)
+  echo "\n##\n## ",i," numbers\n##"
+  let (sd, mean) = sd(n)
+  echo "sd: ",sd,", mean: ",mean
+  histogram(n)