From 1abde5fcd3fde372cdefdc6c967d680a2cc82410 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Sat, 2 Nov 2024 15:19:02 +0100
Subject: Cleaned up and added Index of Coincidence calculator script

---
 ioc.lua | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100755 ioc.lua

diff --git a/ioc.lua b/ioc.lua
new file mode 100755
index 0000000..51c99e2
--- /dev/null
+++ b/ioc.lua
@@ -0,0 +1,62 @@
+#!/usr/bin/env lua
+local eyes = require "eyes"
+local reading = require "reading"
+
+
+local function fmt (float)
+	return string.format("%.5f", float)
+end
+
+
+local function stats (name, parent)
+	return {
+		name=name,
+		parent=parent,
+		letters=0,
+		length=0,
+		counts={},
+
+		add = function (self, value)
+			local current = self.counts[value] or 0
+			if current == 0 then
+				self.letters = self.letters + 1
+			end
+			self.length = self.length + 1
+			self.counts[value] = current + 1
+		end,
+
+		ioc = function (self, letters)
+			letters = letters or self.letters
+			local subtotal = 0
+			for _, count in pairs(self.counts) do
+				subtotal = subtotal + count * (count - 1)
+			end
+			return subtotal / (self.length * (self.length - 1) / letters)
+		end,
+
+		dump = function (self)
+			local letters = (self.parent or {}).letters
+			io.write(name, "\t", self.length, "\t", self.letters, "\t", fmt(self:ioc(letters)))
+			if letters then
+				io.write("\t", fmt(self:ioc()))
+			end
+			print()
+		end
+	}
+end
+
+
+local global = stats"global"
+local lokals = {}
+for index, message in ipairs(eyes) do
+	local lokal = stats("#"..index, global)
+	for _, value in reading.values(message) do
+		global:add(value)
+		lokal:add(value)
+	end
+	table.insert(lokals, lokal)  -- Global is incomplete, can't dump yet.
+end
+global:dump()
+for _, lokal in ipairs(lokals) do
+	lokal:dump()
+end
-- 
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