How to convert the array of objects to array of array with keys

Question

I need to convert the array objects to an array of arrays with its object key of each item of objects as below

var inputData = [{"0":420,"10":373,"20":340,"30":313,"40":293,"50":273,"60":259,"70":243},
                 {"0":620,"10":550,"20":500,"30":460,"40":430,"50":400,"60":378,"70":355},
                 {"0":820,"10":727,"20":660,"30":607,"40":567,"50":527,"60":497,"70":467}]

The above input data of the object has a set of values with keys from which the output array should be like below.

var outputData = [[
                  [0,420],[10,373],[20,340],[30,313],[40,293],[50,273],[60,259],[70,243]
                 ],
                 [
                  [0,620],[10,550],[20,500],[30,460],[40,430],[50,400],[60,378],[70,355]
                 ],
                 [
                  [0,820],[10,727],[20,660],[30,607],[40,567],[50,527],[60,497],[70,467]
                 ]]

for which I had written a for each loop as below code which is returning an entire value in a single array

var inputData = [{"0":420,"10":373,"20":340,"30":313,"40":293,"50":273,"60":259,"70":243}, {"0":620,"10":550,"20":500,"30":460,"40":430,"50":400,"60":378,"70":355},                 {"0":820,"10":727,"20":660,"30":607,"40":567,"50":527,"60":497,"70":467}];

var sp = Object.keys(inputData[0])
let outputData = []
inputData.forEach(i => {
  sp.forEach(element => {
    outputData.push([parseInt(element), i[element]])
  });
})
console.log(outputData)

I made you a snippet. I changed the console.log(outputData) – mplungjan Nov 05 '20 at 07:24 — mplungjan, Nov 05 '20 at 07:24

T.J. Crowder · Answer 1 · 2020-11-05T07:29:20.030

In modern environments with Object.entries (easily polyfilled), this is surprisingly simple: You use map and use Object.entries on each object; then convert the key to a number:

const result = inputData.map(obj => Object.entries(obj).map(([key, value]) => [+key, value]));

Live Example:

var inputData = [{"0":420,"10":373,"20":340,"30":313,"40":293,"50":273,"60":259,"70":243},
                 {"0":620,"10":550,"20":500,"30":460,"40":430,"50":400,"60":378,"70":355},
                 {"0":820,"10":727,"20":660,"30":607,"40":567,"50":527,"60":497,"70":467}];
                 
const result = inputData.map(obj => Object.entries(obj).map(([key, value]) => [+key, value]));
console.log(result);

Note that using the unary + is just one way of converting strings to numbers. In my answer here I go through your various options with their pros and cons.

@NinaScholz - I'd forgotten to convert the keys, but did that a minute ago. — T.J. Crowder, Nov 05 '20 at 07:29

score 2 · Answer 2 · answered Nov 05 '20 at 07:25

You could map the entries of the objects and convert all values to number.

var inputData = [{ 0: 420, 10: 373, 20: 340, 30: 313, 40: 293, 50: 273, 60: 259, 70: 243 }, { 0: 620, 10: 550, 20: 500, 30: 460, 40: 430, 50: 400, 60: 378, 70: 355 },{ 0: 820, 10: 727, 20: 660, 30: 607, 40: 567, 50: 527, 60: 497, 70: 467 }],
    result = inputData.map(o => Object.entries(o).map(a => a.map(Number)));

console.log(result);

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score 1 · Answer 3 · edited Nov 05 '20 at 07:26

You can use Object.entries to generate [key, value] pairs from object.

var inputData = [{"0":420,"10":373,"20":340,"30":313,"40":293,"50":273,"60":259,"70":243}, {"0":620,"10":550,"20":500,"30":460,"40":430,"50":400,"60":378,"70":355},                 {"0":820,"10":727,"20":660,"30":607,"40":567,"50":527,"60":497,"70":467}];


const output = inputData.map((item) => Object.entries(item)).map((item) => item.map(([key, value]) => ([+key, +value])));
console.log(output);

How to convert the array of objects to array of array with keys

3 Answers3