feat(manga): new estimation methods

1 files changed, 52 insertions, 19 deletions

diff --git a/src/lib/AniList/media.ts b/src/lib/AniList/media.ts
index 8cc9c9c8..1ae33f7c 100644
--- a/src/lib/AniList/media.ts
+++ b/src/lib/AniList/media.ts
@@ -196,10 +196,45 @@ export const publicMediaListCollection = async (userId: number, type: Type): Pro
 	return flattenLists(userIdResponse['data']['MediaListCollection']['lists']);
 };
 
+const countMedian = (guesses: number[]) => {
+	guesses.sort((a: number, b: number) => a - b);
+
+	const mid = Math.floor(guesses.length / 2);
+
+	return guesses.length % 2 !== 0 ? guesses[mid] : (guesses[mid - 1] + guesses[mid]) / 2;
+};
+
+const countIQR = (guesses: number[]) => {
+	guesses.sort((a: number, b: number) => a - b);
+
+	const q1 = guesses[Math.floor(guesses.length / 4)];
+	const q3 = guesses[Math.ceil(guesses.length * (3 / 4))];
+	const iqr = q3 - q1;
+
+	return guesses.filter((guess: number) => guess >= q1 - 1.5 * iqr && guess <= q3 + 1.5 * iqr);
+};
+
+const countMode = (guesses: number[]) => {
+	const frequency: { [key: number]: number } = {};
+	let maximumFrequency = 0;
+	let mode = 0;
+
+	for (const guess of guesses) {
+		frequency[guess] = (frequency[guess] || 0) + 1;
+
+		if (frequency[guess] > maximumFrequency) {
+			maximumFrequency = frequency[guess];
+			mode = guess;
+		}
+	}
+
+	return mode;
+};
+
 export const recentMediaActivities = async (
 	userIdentity: UserIdentity,
 	media: Media,
-	method: 'median' | 'trimmed_mean' | 'weighted_average' = 'trimmed_mean'
+	method: 'median' | 'iqr_median' | 'iqr_mode' | 'mode'
 ): Promise<number | null> => {
 	const activities = await (
 		await fetch('https://graphql.anilist.co', {
@@ -235,34 +270,32 @@ export const recentMediaActivities = async (
 	guesses.sort((a, b) => b - a);
 
 	if (guesses.length) {
-		let bestGuess = guesses[0];
+		let bestGuess;
 
 		switch (method) {
 			case 'median':
 				{
-					const sortedGuesses = guesses.slice().sort((a, b) => a - b);
-
-					bestGuess = sortedGuesses[Math.floor(sortedGuesses.length / 2)];
+					bestGuess = countMedian(guesses);
+				}
+				break;
+			case 'iqr_median':
+				{
+					bestGuess = countMedian(countIQR(guesses));
+				}
+				break;
+			case 'iqr_mode':
+				{
+					bestGuess = countMode(countIQR(guesses));
 				}
 				break;
-			case 'trimmed_mean':
+			case 'mode':
 				{
-					const sortedGuesses = guesses.slice().sort((a, b) => a - b);
-					const trimmedGuesses = sortedGuesses.slice(1, -1);
-					bestGuess = trimmedGuesses.reduce((a, b) => a + b) / trimmedGuesses.length;
+					bestGuess = countMode(guesses);
 				}
 				break;
-			case 'weighted_average':
+			default:
 				{
-					const countMap: { [key: number]: number } = {};
-					guesses.forEach((g) => {
-						countMap[g] = (countMap[g] || 0) + 1;
-					});
-
-					bestGuess =
-						Object.entries(countMap).reduce((acc: number, [val, count]: [string, number]) => {
-							return acc + Number(val) * Math.log(count);
-						}, 0) / Object.values(countMap).reduce((a: number, b: number) => a + Math.log(b), 0);
+					bestGuess = countMedian(guesses);
 				}
 				break;
 		}