mediocre-blog/assets/trading-in-the-rain/Distributor.js
2020-04-26 18:15:15 -06:00

43 lines
1.1 KiB
JavaScript

function distribute(val, minOld, maxOld, minNew, maxNew) {
let scalar = (val - minOld) / (maxOld - minOld);
return minNew + ((maxNew - minNew) * scalar);
}
function Distributor(capacity) {
this.cap = capacity;
this.reset = () => {
this.arr = [];
this.arrSorted = [];
this.length = 0;
};
this.reset();
// add adds the given value into the series, shifting off the oldest value if
// the series is at capacity.
this.add = (val) => {
this.arr.push(val);
if (this.arr.length >= this.cap) this.arr.shift();
this.arrSorted = this.arr.slice(); // copy array
this.arrSorted.sort();
this.length = this.arr.length;
};
// distribute finds where the given value falls within the series, and then
// scales that into the given range (inclusive).
this.distribute = (val, min, max) => {
if (this.length == 0) throw "cannot locate within empty Distributor";
let idx = this.length;
for (i in this.arrSorted) {
if (val < this.arrSorted[i]) {
idx = i;
break;
}
}
return distribute(idx, 0, this.length, min, max);
};
}