Parse data into JavaScript arrays

Question

I have an array data format coming from back-end which looks like:

Array
[{"ckey::"C1","date":"0506","rows":17},
 {"ckey::"C1","date":"0706","rows":7},
 {"ckey::"C2","date":"0706","rows":13},
 {"ckey::"C2","date":"0806","rows":11}]

So for few days C1 data is there and few days C2 data. Only one day has C1 and C2 data both.

I want to build an array like for C1 and C2

[[17,7,0],[0,13,11]]

First nested array for C1 where third value is 0 because for 0806 date the value was not present.

Second nested array for C2 where first value is 0 because for 0506 date the value was not present.

Please help. I cannot form the array effectively.

I think it would be O(n^3) solution. But please help with the same.

UPDATE

Here was my approach, I could not post the code here but it looks something like this.

I was getting date values in separate array like and I filter for unique days.

 angular.forEach(data, function(obj){
 if(timeData.indexOf(obj.date) === -1)
 timeData.push(obj.date);
 });

Then ckey array _distinctckeyArray also were there containing values ["C1","C2"].

angular.forEach(_distinctckeyArray,function(_ckey){
 var _formattedDataArrItem = [];
 angular.forEach(timeData,function(_dateTimeString) {
 var _tempDataVolume = [];
 angular.forEach(_data,function(_dataObj) {
 if(_dataObj.date === _dateTimeString) {
 if(_dataObj.ckey === _ckey) {
 _tempDataVolume.push(_dataObj.rows);
 }else {
 _tempDataVolume.push(0);
 }
 }
 });
 });

• T.J. Crowder: If the data from the backend really looks like you've shown, it's not JSON -- or at least, not valid JSON. The quotes are unbalanced.
• StrugglingCoder: @T.J.Crowder It's a real array and we can loop through the array. I just depicted the data format but it is real JS array of objects.
• T.J. Crowder: Then you might want to fix the question. It's also unclear what you're asking. If it's an array of objects, it's not JSON. JSON is a textual notation for data exchange. (More here.) If you're dealing with JavaScript source code, and not dealing with a string, you're not dealing with JSON.
• StrugglingCoder: @T.J.Crowder Sorry for the confusion. It's not a JSON data. I have updated the title.
• simbathesailor: i dint understabd this line "First nested array for C1 where third value is 0 because for 0806 date the value was not present.". Could you please make it clear.

Answer 1

You can make an object dates that will have date properties. Initialize the values to 0

You reduce to group the array. Use Object.values to convert the object into an array.

let arr = [{ckey:"C1","date":"0506","rows":17},{ckey:"C1","date":"0706","rows":7},{ckey:"C2","date":"0706","rows":13},{ckey:"C2","date":"0806","rows":11}];
//Make an object with property dates. assign all property to 0 as initial value.
//Expected output:
//{"0506":0,"0706":0,"0806":0}
let dates = arr.reduce((c, v) => Object.assign(c, {[v.date]: 0}), {});
//Loop thru the array using `reduce`. 
//This is to group the array to object using the ckey as the key
//After grouping, use `Object.values` to convert the object into array
let result = Object.values(arr.reduce((c, {ckey,date,rows}) => {
 c[ckey] = c[ckey] || { ...dates }; //Check if c[ckey] exist. If it does not, "clone" the dates object.
 c[ckey][date] = rows; //Overide the initial value 0 to the rows value
 return c;
}, {})).map(o => Object.values(o));
console.log(result);

• StrugglingCoder: Could you please explain? It would greatly help me.
• Eddie: @StrugglingCoder I added an explanation. Please let me know if you have a Q

Answer 2

I think this is what you are looking for. Let me know.

let data = [{
 'ckey': 'C1',
 'date': '0506',
 'rows': 17
}, {
 'ckey': 'C1',
 'date': '0706',
 'rows': 7
}, {
 'ckey': 'C2',
 'date': '0706',
 'rows': 13
}, {
 'ckey': 'C2',
 'date': '0806',
 'rows': 11
}]
function nested_arrays(array) {
 const result = []
 const obj = {
 c1: [],
 c2: []
 }
 for (let i = 0; i < array.length; i++) {
 if (array[i].ckey === 'C1') {
 obj.c1.push(array[i].rows)
 }
 if (array[i].ckey === 'C2') {
 obj.c2.push(array[i].rows)
 }
 }
 obj.c1.push(0) // set last value to 0
 obj.c2.unshift(0) // set first value to 0
 result.push(obj.c1, obj.c2)
 return result
}
let _tempDataVolume = nested_arrays(data)
console.log(_tempDataVolume) //=> [ [ 17, 7, 0 ], [ 0, 13, 11 ] ]

Answer 3

let arr = [{"ckey::"C1","date":"0506","rows":17},
 {"ckey::"C1","date":"0706","rows":7},
 {"ckey::"C2","date":"0706","rows":13},
 {"ckey::"C2","date":"0806","rows":11}]
 arr.map(res =>{ 
let c1arr = [],
 let c2arr = [], 
 if(res.ckey== 'C1'){ 
 c1arr.push(res.rows) 
 }else{ c2arr.push(res.rows) }
 })
let newArrr = []
newArr.push(c1arr);
newArr.push(c2arr);
console.log('arr is',newArr)