How to concat sub array in typescript or javascript?

Question

How to concat sub array in typescript or javascript? In may case I want concat all values with same name.

My array is

[
  {
    name: "AAA"
    values: [[1573054321, 0], [1573054560, 0]]
  }, {
    name: "BBB"
    values: [[1573054388, 0], [1573054596, 0]]
  }
], [
  {
    name: "AAA"
    values: [[1573054355, 0], [1573054542, 0]]
  }, {
    name: "BBB"
    values: [[1573054325, 0], [1573054545, 0]]
  }
]

I want this in my output:

[
  {
    name: "AAA"
    values: [[1573054321, 0], [1573054560, 0], [1573054355, 0], [1573054542, 0]]
  }, {
    name: "BBB"
    values: [[1573054388, 0], [1573054596, 0], [1573054325, 0], [1573054545, 0]]
  }
]

My typescript exemple with a simple concat (allMetricSeries is my input):

let metricSeries: MetricSeries[] = [];
allMetricSeries.forEach(metrics => {
  metricSeries = metricSeries.concat(metrics);
});

Is this the answer for your question? https://stackoverflow.com/a/33850667/12283811 — tunapq, Nov 08 '19 at 13:46
@tunapq, is it not the same case, I have an array of array!! You read too quickly — Stéphane GRILLON, Nov 08 '19 at 13:56
@Nicolas, I have already done a simplification extraction job to post this question. My case is a lot more complicated in my application. Thank you for your reply. — Stéphane GRILLON, Nov 08 '19 at 14:22
@sgrillon I understand, i just felt it was kind of rude to tell us that our solutions are wrong, we did most of what you've ask, now you can take that and adjust it to you need. — Nicolas, Nov 08 '19 at 14:24

Nicolas · Accepted Answer · 2019-11-08T14:08:04.793

You can use a simple loop with a new array to accomplish this.

let array = [
  [{
    name: "AAA",
    values: [[1573054321, 0], [1573054560, 0]]
  }, 
  {
    name: "BBB",
    values: [[1573054388, 0], [1573054596, 0]]
  }],
  [{
    name: "AAA",
    values: [[1573054355, 0], [1573054542, 0]]
  }, 
  {
    name: "BBB",
    values: [[1573054325, 0], [1573054545, 0]]
  }]
];

let output = {};
// we loop every array
array.forEach((subArray) => {
  // we loop every array of array
  subArray.forEach((data) => {
  // if the key does not exists, we create it.
   if(!output.hasOwnProperty(data.name)) {
      output[data.name] = {
        name: data.name,
        values: []
      };
    }
    // push the value.
     output[data.name].values = output[data.name].values.concat(data.values);
  })
});

// we returns only the values of our object.
console.log(Object.values(output));

your answers is wrong: [ { name: "AAA" values: [[[1573054321, 0], [1573054560, 0]], [[1573054355, 0], [1573054542, 0]]] }, { name: "BBB" values: [[[1573054388, 0], [1573054596, 0]], [[1573054325, 0], [1573054545, 0]]] } ] — Stéphane GRILLON, Nov 08 '19 at 14:07
@sgrillon I've change my answer for something more suitable. — Nicolas, Nov 08 '19 at 14:08

Anis R. · Answer 2 · 2019-11-08T14:13:36.787

One way would be to first build a dictionary of the form name => values, and then building our target array from that dictionary (by generating an object of the form {name: values} from each entry in the dictionary)

//your initial array
var arr = [[
  {
    name: "AAA",
    values: [[1573054321, 0], [1573054560, 0]]
  }, {
    name: "BBB",
    values: [[1573054388, 0], [1573054596, 0]]
  }
], [
  {
    name: "AAA",
    values: [[1573054355, 0], [1573054542, 0]]
  }, {
    name: "BBB",
    values: [[1573054325, 0], [1573054545, 0]]
  }
]];

//temporary dictionary to help us build the new array
//of the form {'AAA' => [values], 'BBB' => [values]}
var dict = {};

for(var sub of arr) {
  for(var x of sub) {
    if(dict[x.name]) {
      dict[x.name] = dict[x.name].concat(x.values);
    }
    else {
      dict[x.name] = x.values;
    }
  }
}

//now building the new array from the dictionary:
var new_arr = [];
for (key in dict) {
  new_arr.push({name:key, values:dict[key]});
}

console.log(new_arr);

@sgrillon Oh, I thought you wanted a flat array! Answer updated. — Anis R., Nov 08 '19 at 14:13

score 0 · Answer 3 · answered Nov 08 '19 at 13:52

One way of doing it.

resultObj = {};
[[
  {
    name: "AAA",
    values: [[1573054321, 0], [1573054560, 0]]
  }, {
    name: "BBB",
    values: [[1573054388, 0], [1573054596, 0]]
  }
], [
  {
    name: "AAA",
    values: [[1573054355, 0], [1573054542, 0]]
  }, {
    name: "BBB",
    values: [[1573054325, 0], [1573054545, 0]]
  }
]].forEach((subArray) => {
    subArray.forEach((arr) => {
        const name = arr.name;
        if (!resultObj[name]) {
            resultObj[name] = arr.values.slice();
        } else {
            resultObj[name].push(...arr.values);
        }
    });
});
finalResult = Object.keys(resultObj).map((key) => {
    return {name: key, values: resultObj[key]}
});

score 0 · Answer 4 · answered Nov 08 '19 at 15:10

Another way through reduce method and spread operator:

let data = [
    [
        {
            name: "AAA",
            values: [[1573054321, 0], [1573054560, 0]]
        }, {
            name: "BBB",
            values: [[1573054388, 0], [1573054596, 0]]
        }
    ],
    [
        {
            name: "AAA",
            values: [[1573054355, 0], [1573054542, 0]]
        }, {
            name: "BBB",
            values: [[1573054325, 0], [1573054545, 0]]
        }
    ]
];


const result = data.reduce((a, c) => {
    let innerResult = c.reduce((ia, ic) => {
        ia[ic.name] = ia[ic.name] || {name: ic.name, values:[]};
        ia[ic.name].values.push(ic.values);
        return ia;
    }, {});

    for (const key in innerResult) {
        a[key] = a[key] || {values: []};
        a[key].values.push(...innerResult[key].values);
    }
    return a;
}, {});    
console.log(result);

How to concat sub array in typescript or javascript?

4 Answers4