Iterate through an Array of Objects and output custom object

Question

I am needing to build a custom object from an array of objects in Typescript.

In the giving example below, How do I count how many times the salesman_1_name is in the Array, Add the gross for each Salesman_1_name, and count if warranty is not null for each salesman_1_name? So if I have:

[
    {salesman_1_name:Brian, gross:100, warranty: Easycare},
    {salesman_1_name:Brian, gross:100, warranty: Easycare},
    {salesman_1_name:Brian, gross:100, warranty: null},
    {salesman_1_name:Kreso, gross:100, warranty: null},
    {salesman_1_name:Filip, gross:100, warranty: Easycare}
]

I would need to output:

[
    Name:Brian, Count:3, Gross:300, WarrantyCount:2, 
    Name:Kreso, Count:1, Gross:100, WarrantyCount:0, 
    Name:Filip, Count:1, Gross:100, WarrantyCount:1
]

is Easycare a string? where do you get WarrantyCount from? — Nina Scholz
– Nina Scholz, Commented Sep 23, 2016 at 12:02
Yes, I meant to add warranty names to two of the "Brian" lines in the example. I would need to count if warranty is not null and count++ — BHead
– BHead, Commented Sep 23, 2016 at 12:04
why do you get Filip ... WarrantyCount:1 and Brian ... WarrantyCount:2? — Nina Scholz
– Nina Scholz, Commented Sep 23, 2016 at 12:10
Edited, I left the string out of warranty in the example. I just edited. — BHead
– BHead, Commented Sep 23, 2016 at 12:20

yjcxy12 · Accepted Answer · 2016-09-23 12:27:45Z

1

data.reduce((acc, cur) => {
  const obj = acc.find(x => x.Name === cur.salesman_1_name);
  if (obj) {
    obj.Gross += cur.gross;
    obj.WarrantyCount = cur.warranty !== null ? obj.WarrantyCount + 1 : obj.WarrantyCount;
  } else {
    acc.push({ Name: cur.salesman_1_name, Gross: cur.gross, WarrantyCount: cur.warranty !== null ? 1 : 0 });
  }
  return acc;
}, []);

answered Sep 23, 2016 at 12:27

yjcxy12

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1 Comment

Peter Seliger Over a year ago

with each iteration step of reduce one really does not want and one also is not in need of searching for the related salesman item within the accumulating list.

Nina Scholz · Accepted Answer · 2016-09-23 12:34:57Z

1

You could use an object as reference to the group with the name and make your aggregation.

var data = [{ salesman_1_name: 'Brian', gross: 100, warranty: 'Easycare' }, { salesman_1_name: 'Brian', gross: 100, warranty: 'Easycare' }, { salesman_1_name: 'Brian', gross: 100, warranty: null }, { salesman_1_name: 'Kreso', gross: 100, warranty: null }, { salesman_1_name: 'Filip', gross: 100, warranty: 'Easycare' }],
    grouped = [];

data.forEach(function (a) {
    if (!this[a.salesman_1_name]) {
        this[a.salesman_1_name] = { Name: a.salesman_1_name, Count: 0, Gross: 0, WarrantyCount: 0 };
        grouped.push(this[a.salesman_1_name]);
    }
    this[a.salesman_1_name].Count++;
    this[a.salesman_1_name].Gross += a.gross;
    a.warranty !== null && this[a.salesman_1_name].WarrantyCount++;    
}, Object.create(null));

console.log(grouped);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Sep 23, 2016 at 12:34

answered Sep 23, 2016 at 12:14

Nina Scholz

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3 Comments

Peter Seliger Over a year ago

1/2: I mostly like your approaches, but this time I will be nitpicking. reduce should be the preferred approach. There are 2 arguments for it. The approach uses and additional target-object (why Object.create(null) instead of a plain object literal {}) as a map or accumulator object that one needs to refer to as this (thats usage/purpose for many people is also not quite obvious even at second glance) ...

Peter Seliger Over a year ago

2/2: ... On the other hand, the code still need to stick to an grouped outside object as final accumulator object. With reduce one gets everything for free and the callback's code becomes more elegant and far more reusable.

Nina Scholz Over a year ago

if i have a hash like toString, then the check for existence leads to wrong results. i use forEach, because of the nature of reduce, which is in this example always the same, a reference to the result set, which is not really changing, like somthing as a sum or a single primitive/changing object.

Vladu Ionut · Accepted Answer · 2016-09-23 13:56:21Z

0

// Code goes here

var data = [{
  salesman_1_name: 'Brian',
  gross: 100,
  warranty: 'Easycare'
}, {
  salesman_1_name: 'Brian',
  gross: 100,
  warranty: 'Easycare'
}, {
  salesman_1_name: 'Brian',
  gross: 100,
  warranty: null
}, {
  salesman_1_name: 'Kreso',
  gross: 100,
  warranty: null
}, {
  salesman_1_name: 'Filip',
  gross: 100,
  warranty: 'Easycare'
}];


var result = (function(myArray) {
  var obj = []; //also can be used Object.values(dataCollector)
  var dataCollector = myArray.reduce(function(dataCollector, currentItem ) {

    if (!dataCollector[currentItem['salesman_1_name']]) {
      dataCollector[currentItem['salesman_1_name']] = {
        Name: currentItem.salesman_1_name,
        Count: 0,
        Gross: currentItem.gross,
        WarrantyCount: currentItem['salesman_1_name'].warranty != null ? 0 : 1
      };

    } else {
      dataCollector[currentItem['salesman_1_name']].Count++;
      dataCollector[currentItem['salesman_1_name']].Gross += currentItem.gross;
      if (currentItem['salesman_1_name'].warranty !== null) {
        dataCollector[currentItem['salesman_1_name']].WarrantyCount++;
      }

    }

    return dataCollector;

  }, {});

  for (var key in dataCollector) {
    if (dataCollector.hasOwnProperty(key)) {
      obj.push(dataCollector[key]);
    }
  }
  return obj;

})(data)

console.log(result);

edited Sep 23, 2016 at 13:56

answered Sep 23, 2016 at 12:40

Vladu Ionut

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1 Comment

Peter Seliger Over a year ago

@Vladulonut ... uhh ... two exit points - return obj and return dataCollector - together with a final condition for the early exit that needs to be processed with each iteration of reduce ... reduce and its accumulator object really can be used more elegantly ... also with the final condition, one is not in need of referring to the outside list, since it gets provided as 4th argument of the reduce's callback function, thus making it possible referring the reduced list from inside this callback and processing arrays that are not yet known by name.

Peter Seliger · Accepted Answer · 2016-09-23 15:00:27Z

var rawSalesmanData = [
    { salesman_1_name: "Brian", gross: 100, warranty: "Easycare" },
    { salesman_1_name: "Brian", gross: 100, warranty: "Easycare" },
    { salesman_1_name: "Brian", gross: 100, warranty: null },
    { salesman_1_name: "Kreso", gross: 100, warranty: null },
    { salesman_1_name: "Filip", gross: 100, warranty: "Easycare" }
];

var salesmanSpecificList = rawSalesmanData.reduce(function (collector, rawDataItem/*, idx, rawDataList*/) {

    var map       = collector.map;
    var key       = rawDataItem.salesman_1_name;
    var namedItem = map[key];

    if (!namedItem) {
        namedItem = map[key] = {
            name            : key,
            occurencyCount  : 0,
            grossTotal      : 0,
            warrantyCount   : 0
        };
        collector.list.push(namedItem);
    }
    namedItem.occurencyCount++;
    namedItem.grossTotal = (namedItem.grossTotal + rawDataItem.gross);
    namedItem.warrantyCount = (namedItem.warrantyCount + ((rawDataItem.warranty !== null) ? 1 : 0));

    return collector;

}, {

    map : {},
    list: []

}).list;


console.log("salesmanSpecificList : ", salesmanSpecificList);

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