Animal Crossing Stalk Market Analyzer

Animal Crossing games feature a weekly "stalk market" with a simple premise: purchase turnips on Sunday, then figure out when to (hopefully) sell them for a profit before the following Sunday. This is a simple library to help predict when you should sell your turnips!

The logic contained within this library was inspired by this stalk market guide on Thonky: https://www.thonky.com/animal-crossing-new-leaf/stalk-market

Intro to selling

Turnip sell prices update twice a day, once at store opening and another one at 12pm. Assuming the store is closed on Sundays, that gives twelve opportunities to record turnip pricing throughout the week:

      M  T  W  T  F  S
 6am  1  3  5  7  9  11
12pm  2  4  6  8  10 12

If turnips are not sold by 6am on the following Sunday, they spoil and lose all value!

Figuring out when to sell

After recording a few sell prices, pass them into this library's analyze() method:

import analyze from 'ac-stalk-market-analyzer';

const prices = [73, 72, 69, 80, 92, 112, 98, 95, 35, 32, 20, 17];
const pattern = analyze(prices);

The return value will be one of the following strings:

"spikeBig"

A series of three increases, with the third increase being the maximum sell price. The following two decreases are higher than the average sell price, giving you an opportunity to realize a smaller return before the remaining price decreases rob you of an opportunity for profit.

"spikeSmall"

This pattern is similar to spikeBig, but is a series of four increases followed by only a single decrease higher than the average, before decreasing from there on.

"decreasing"

Every sell price change is lower than the one before. If no increase occurs throughout the week, you should sell by Thursday afternoon.

"random"

Pricing is unpredictable. Pricing will likely jump randomly between 50 and 200 bells.

"unknown"

There's not enough pricing data to determine a pattern. This is common when some prices are not recorded. The library may still be able to detect a pattern even if you skip recording a couple of prices, though!