average.js•1.28 kB
import converter from './converter.js';
import { getMode } from './modes.js';
const averageAngle = val => {
// See: https://en.wikipedia.org/wiki/Mean_of_circular_quantities
let sum = val.reduce(
(sum, val) => {
if (val !== undefined) {
let rad = (val * Math.PI) / 180;
sum.sin += Math.sin(rad);
sum.cos += Math.cos(rad);
}
return sum;
},
{ sin: 0, cos: 0 }
);
return (Math.atan2(sum.sin, sum.cos) * 180) / Math.PI;
};
const averageNumber = val => {
let a = val.filter(v => v !== undefined);
return a.length ? a.reduce((sum, v) => sum + v, 0) / a.length : undefined;
};
const isfn = o => typeof o === 'function';
function average(colors, mode = 'rgb', overrides) {
let def = getMode(mode);
let cc = colors.map(converter(mode));
return def.channels.reduce(
(res, ch) => {
let arr = cc.map(c => c[ch]).filter(val => val !== undefined);
if (arr.length) {
let fn;
if (isfn(overrides)) {
fn = overrides;
} else if (overrides && isfn(overrides[ch])) {
fn = overrides[ch];
} else if (def.average && isfn(def.average[ch])) {
fn = def.average[ch];
} else {
fn = averageNumber;
}
res[ch] = fn(arr, ch);
}
return res;
},
{ mode }
);
}
export { average, averageAngle, averageNumber };