Gremlins

code/__HELPERS/markov.dm

@@ -0,0 +1,61 @@
+#define MAXIMUM_MARKOV_LENGTH 25000
+
+/proc/markov_chain(var/text, var/order = 4, var/length = 250)
+	if(!text || order < 0 || order > 20 || length < 1 || length > MAXIMUM_MARKOV_LENGTH)
+		return
+
+	var/table = markov_table(text, order)
+	var/markov = markov_text(length, table, order)
+	return markov
+
+/proc/markov_table(var/text, var/look_forward = 4)
+	if(!text)
+		return
+	var/list/table = list()
+
+	for(var/i = 1, i <= length(text), i++)
+		var/char = copytext(text, i, look_forward+i)
+		if(!table[char])
+			table[char] = list()
+
+	for(var/i = 1, i <= (length(text) - look_forward), i++)
+		var/char_index = copytext(text, i, look_forward+i)
+		var/char_count = copytext(text, i+look_forward, (look_forward*2)+i)
+
+		if(table[char_index][char_count])
+			table[char_index][char_count]++
+		else
+			table[char_index][char_count] = 1
+
+	return table
+
+/proc/markov_text(var/length = 250, var/table, var/look_forward = 4)
+	if(!table)
+		return
+	var/char = pick(table)
+	var/o = char
+
+	for(var/i = 0, i <= (length / look_forward), i++)
+		var/newchar = markov_weighted_char(table[char])
+
+		if(newchar)
+			char = newchar
+			o += "[newchar]"
+		else
+			char = pick(table)
+
+	return o
+
+/proc/markov_weighted_char(var/list/array)
+	if(!array || !array.len)
+		return
+
+	var/total = 0
+	for(var/i in array)
+		total += array[i]
+	var/r = rand(1, total)
+	for(var/i in array)
+		var/weight = array[i]
+		if(r <= weight)
+			return i
+		r -= weight