const myObj = {
a: [1, 2, 3],
b: [2, 4, 6],
c: [10, 20, 30]
}
Into
const myCollection = [
{a: 1, b: 2, c: 10},
{a: 2, b: 4, c: 20},
{a: 3, b: 6, c: 30}
]
I tried combinations of Object.entries, Object.keys and map but I'm always finding myself iterating twice or more over myObj and I'm not happy with any solution I came up with.
So what is the most efficient (in terms of time complexity) and elegant way that you can think to achieve that?
Just in case you'd need variable length:
const myObj = {
a: [1, 2, 3],
b: [2, 4, 6,8, 10],
c: [10, 20, 30, 40],
};
let myCollection = [];
Object.keys(myObj).forEach((k) => {
for (let i = 0; i < myObj[k].length; i++) {
if (!myCollection[i]) myCollection.push({});
myCollection[i][k] = myObj[k][i];
}
});
console.log(myCollection);You could reduce the entries and map nested arrays.
const
object = { a: [1, 2, 3], b: [2, 4, 6], c: [10, 20, 30] },
result = Object
.entries(object)
.reduce((r, [k, a]) => a.map((v, i) => ({ ...r[i], [k]: v })), []);
console.log(result);That can be done using Array.reduce. I have attached the conversion code.
const myObj = {
a: [1, 2, 3],
b: [2, 4, 6],
c: [10, 20, 30]
}
const myCollection = [
{a: 1, b: 2, c: 10},
{a: 2, b: 4, c: 20},
{a: 3, b: 6, c: 30}
]
const maxLength = Math.max(...Object.values(myObj).map(item => item.length));
const myObjKeys = Object.keys(myObj);
const result = [ ...Array(maxLength).keys() ].map((index) => {
return myObjKeys.reduce((acc, curKey) => {
if (myObj[curKey].length > index) {
acc[curKey] = myObj[curKey][index];
}
return acc;
}, {});
});
console.log(result);Using ramdajs, I could suggest you a short way like below
const myObj = {
a: [1, 2, 3],
b: [2, 4, 6],
c: [10, 20, 30]
}
const res = R.map(
R.zipObj(R.keys(myObj)),
R.values(myObj)
)
console.log(res)<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>In ramdajs homepage, criteria 3 in What's Different, it cited that
The parameters to Ramda functions are arranged to make it convenient for currying. The data to be operated on is generally supplied last.
You can use map() on Object.values and then use reduce() on each value.
const myObj = {
a: [1, 2, 3],
b: [2, 4, 6],
c: [10, 20, 30]
}
let keys = Object.keys(myObj);
const arr = Object.values(myObj).map((a) => a.reduce((ac, a, i) => ({...ac, [keys[i]]:a}), {}));
console.log(arr)