I have an array of pairs that looks like this [[x,y], [x,y] ... ]. I want to format it into an Object where the values are arrays of x and y values like so {keys: [x1, x2, x3 ...], values: [y1, y2, y3 ... ]}.
Are there any array/object operations to complete this operation without iterating through the original list?
The easiest and safest way is to reduce the array to an object, although it requires a loop:
const input = [[3, 300], [2, 200], [1, 100]];
const result = input.reduce((acc, [key, val]) => {
acc.keys.push(key);
acc.values.push(val);
return acc;
}, { keys: [], values: [] });
console.log(result);I wouldn't actually use the convert to object / Map method (under Original Answer), because it has a serious caveat - duplicate entries the has the same keys would be overridden.
For example:
const input = [[3, 300], [3, 200], [3, 100]];
const obj = Object.fromEntries(input);
const result = { keys: Object.keys(obj), values: Object.values(obj) };
console.log(result);Building on top of pilchard's answer, I would convert the array to a Map, and then take the Map's keys, and values. I would use a Map, and not an object, because object's keys are always strings, and if the values are integers, the object would also be sorted by their value. A Map would preserve the original type, and won't reorder them.
const input = [[3, 300], [4, 200], [1, 100]];
const map = new Map(input);
const result = { keys: [...map.keys()], values: [...map.values()] };
console.log(result);An example of converting the same structure to an object:
const input = [[3, 300], [4, 200], [1, 100]];
const obj = Object.fromEntries(input);
const result = { keys: Object.keys(obj), values: Object.values(obj) };
console.log(result);The process is iterative, but you can hide it by using existing Object methods: Object.fromEntries(), Object.keys(), Object.values()
const input = [['a', 1], ['b', 2], ['c', 3]];
const obj = Object.fromEntries(input);
const result = { keys: Object.keys(obj), values: Object.values(obj) };
console.log(result);Ori Drori's refinement using a Map is more robust not only for numeric values but for any type.
const input = [[new Date(), { y: 1 }], [new Date(), { y: 2 }], [new Date(), { y: 3 }]];
const map = new Map(input);
const result = { keys: [...map.keys()], values: [...map.values()] };
console.log(result);
console.log(result.keys[0].valueOf());No space left for losers, but just another way
const input = [[3, 300], [4, 200], [1, 100]];
const result = { keys: Array.from(input, x => x[0]), values: Array.from(input, x => x[1]) };
console.log(result);