Implementing weighted random

examples/simple_space_example.html

@@ -123,7 +123,8 @@ StoryManager.getAllStorylets = function(tag=null) {
 	return allStorylets;
 }
 
-StoryManager.getStorylets = function(n=null, tag=null, respect_interrupt=true) {
+StoryManager.getStorylets = 
+	function(n=null, tag=null, selection="ordered", respect_interrupt=true) {
 	/* 
 		Get n storylets, prioritizing the highest-priority ones first.
 
@@ -143,12 +144,24 @@ StoryManager.getStorylets = function(n=null, tag=null, respect_interrupt=true) {
 			if (allStorylets[i].interrupt) return [allStorylets[i]];
 	}
 
-	// Get n stories in priority order
+	// Return n or the max
 	if (n != null) {
 		n = Math.min(n, allStorylets.length);
 		if (n == 0) return [];
 	}
 	else n = allStorylets.length;
+
+	let selectedStorylets;
+	if (selection == "ordered") 
+		selectedStorylets = this.sortByPriority(allStorylets, n);
+	else if (selection == "weighted")
+		selectedStorylets = this.weightedRandom(allStorylets, n);
+		
+	return selectedStorylets;
+}
+
+// Get storylets strictly by priority
+StoryManager.sortByPriority = function(allStorylets, n) {
 	let selectedStorylets = [];
 
 	// Select by strict priority; randomize among matching priority.
@@ -166,19 +179,40 @@ StoryManager.getStorylets = function(n=null, tag=null, respect_interrupt=true) {
 	return selectedStorylets;
 }
 
-// Set up macros
+// Get storylets via weighted random choice
+StoryManager.weightedRandom = function(allStorylets, n) {
+	let selectedStorylets = [];
+	let sum, counter, index, rand;
+	while (selectedStorylets.length < n) {
+		sum = allStorylets.reduce((a, x) => a + x.priority, 0);
+		counter = 0;
+		rand = Math.random() * sum;
+		for (let i=0; i<allStorylets.length; i++) {
+			if (counter + allStorylets[i].priority)  {
+				selectedStorylets.push(allStorylets.splice(i, 1));
+				break;
+			}
+			counter += allStorylets[i].priority;
+		}
+	}
+	return selectedStorylets;
+}
 
+
+
+// Set up macros
+// ---------------------------------------------------------------
 Macro.add("getStoryletLinks", {
 	handler: function() {
 		let n, tag;
 		[n=null, tag=null] = this.args;
 		State.temporary.nextStorylets = StoryManager.getStorylets(n, tag);
 		$(this.output).wiki(`
-		<<for _storylet range _nextStorylets>>
-			<<capture _storylet>>
+		<<for _storylet range _nextStorylets>> \
+			<<capture _storylet>> \
 				[[_storylet.description|_storylet.passage][$currentStorylet=_storylet]]<br>
-			<</capture>>
-		<</for>>
+			<</capture>> \
+		<</for>> \
 		`);
 	}
 })