--- a/util/array.lua	Fri Oct 19 13:31:00 2018 +0100
+++ b/util/array.lua	Sun Oct 21 15:38:55 2018 +0100
@@ -52,6 +52,19 @@
 	return true;
 end
 
+function array_mt.__div(a1, func)
+	local a2 = new_array();
+	local o = 0;
+	for i = 1, #a1 do
+		local new_value = func(a1[i]);
+		if new_value ~= nil then
+			o = o + 1;
+			a2[o] = new_value;
+		end
+	end
+	return a2;
+end
+
 setmetatable(array, { __call = new_array });
 
 -- Read-only methods
@@ -59,6 +72,12 @@
 	return self[math_random(1, #self)];
 end
 
+-- Return a random value excluding the one at idx
+function array_methods:random_other(idx)
+	local max = #self;
+	return self[((math.random(1, max-1)+(idx-1))%max)+1];
+end
+
 -- These methods can be called two ways:
 --   array.method(existing_array, [params [, ...]]) -- Create new array for result
 --   existing_array:method([params, ...]) -- Transform existing array into result