Merge 2 objects in an array where the values are an array

Question

I am trying to merge values in 2 objects from the same array. The objects in this case are similar and the values I want to merge are arrays(Set)

var array = [
  {
  name: "foo1",
  value: ["val1","val2"]
}, 
{
  name: "foo1",
  value: ["val2", "val3"]
}, 
{
  name: "foo2",
  value: ["val4"]
},
 {
  name: "foo2",
  value: ["val4","val5"]
},
];

Expected Output

[
{
  name: "foo1",
  value: ["val1","val2", "val3"]
},{
  name: "foo2",
  value: ["val4","val4", "val5"]
}
]

My Code

var output = [];

array.forEach(function(item) {
  var existing = output.filter(function(v, i) {
    return v.name == item.name;
  });
  if (existing.length) {
    var existingIndex = output.indexOf(existing[0]);
    let newValue = new Set(output[existingIndex].value).add(item.value)
    output[existingIndex].value = Array.from(newValue);
  } else {
    output.push(item);
  }
});

Output Gotten

[ {
  name: "foo1",
  value: ["val1", "val2", ["val2", "val3"]]
}, {
  name: "foo2",
  value: ["val4", ["val4", "val5"]]
}]

How can I get the expected output (ES6 would also be preferred)

The expected output should be value: ["val4", "val5"] instead of value: ["val4","val4", "val5"], is that right? — Md Sabbir Alam
– Md Sabbir Alam, Commented Jan 7, 2021 at 10:31

Naren · Accepted Answer · 2021-01-07 10:22:37Z

2

Try this

const array = [
  {
    "name": "foo1",
    "value": [
      "val1",
      "val2",
      "val3"
    ]
  },
  {
    "name": "foo1",
    "value": [
      "val2",
      "val3"
    ]
  },
  {
    "name": "foo2",
    "value": [
      "val4",
      "val5"
    ]
  },
  {
    "name": "foo2",
    "value": [
      "val4",
      "val5"
    ]
  }
]

const result = []

for (const item of array) {
  const existingItem = result.find(i => i.name === item.name)
  if (existingItem) {
    existingItem.value = [...new Set([...existingItem.value, ...item.value])]
  } else {
    result.push(item)
  }
}

console.log(result)

answered Jan 7, 2021 at 10:22

Naren

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Comments

gscHeartA · Accepted Answer · 2021-01-07 10:22:39Z

1

Is this code solve your problem?

var array = [
    {
    name: "foo1",
    value: ["val1","val2"]
  }, 
  {
    name: "foo1",
    value: ["val2", "val3"]
  }, 
  {
    name: "foo2",
    value: ["val4"]
  },
   {
    name: "foo2",
    value: ["val4","val5"]
  },
  ];

  var output = [];

array.forEach(function(item) {
  var existing = output.filter(function(v, i) {
    return v.name == item.name;
  });
  if (existing.length) {
    var existingIndex = output.indexOf(existing[0]);
    let newValue = new Set(output[existingIndex].value.concat(item.value))
    output[existingIndex].value = Array.from(newValue);
  } else {
    output.push(item);
  }
});

answered Jan 7, 2021 at 10:22

gscHeartA

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Comments

Kartik Narang · Accepted Answer · 2021-01-07 10:28:33Z

1

try

var arr = [
  {
  name: "foo1",
  value: ["val1","val2"]
}, 
{
  name: "foo1",
  value: ["val2", "val3"]
}, 
{
  name: "foo2",
  value: ["val4"]
},
 {
  name: "foo2",
  value: ["val4","val5"]
},
];
var arr2={}
arr.map((elem,ind)=>{
    if(!arr2[elem.name]){
        arr2[elem.name]=[]
    }
    arr2[elem.name]=[...arr2[elem.name],...elem.value]
})
arr=Object.keys(arr2);
arr.map((elem,ind)=>{
    arr[ind]={name:elem,value:arr2[elem]};
})

answered Jan 7, 2021 at 10:28

Kartik Narang

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Comments

Md Sabbir Alam · Accepted Answer · 2021-01-07 10:30:42Z

1

You can do the following using reduce,

var array = [
  {
  name: "foo1",
  value: ["val1","val2"]
}, 
{
  name: "foo1",
  value: ["val2", "val3"]
}, 
{
  name: "foo2",
  value: ["val4"]
},
 {
  name: "foo2",
  value: ["val4","val5"]
},
];

res = array.reduce((prev, curr) => {
  let index = prev.findIndex(item => item.name === curr.name);
 
  if(index > -1) {
    s = new Set([...prev[index].value, ...curr.value]);
    prev[index].value = Array.from(s);
  } else {
    prev.push(curr);
  }
  return prev;
},[]);

console.log(res);

edited Jan 7, 2021 at 10:30

answered Jan 7, 2021 at 10:24

Md Sabbir Alam

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Comments

Nenad Vracar · Accepted Answer · 2021-01-07 10:35:50Z

1

You could use reduce method with a Map as accumulator value and then use spread syntax ... on Map values to get an array of values.

var array = [{"name":"foo1","value":["val1","val2","val2","val3"]},{"name":"foo1","value":["val2","val3"]},{"name":"foo2","value":["val4","val4","val5"]},{"name":"foo2","value":["val4","val5"]}]

const map = array.reduce((r, { name, value }) => {
  if (!r.has(name)) r.set(name, { name, value })
  else r.get(name).value.push(...value)
  r.get(name).value = [...new Set(r.get(name).value)]
  return r;
}, new Map)

const result = [...map.values()]

console.log(result)

edited Jan 7, 2021 at 10:35

answered Jan 7, 2021 at 10:26

Nenad Vracar

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Comments

Thomas Sablik · Accepted Answer · 2021-01-07 11:06:19Z

One approach is to create an unique list of keys and iterate over it. Create an array for each key and merge the values. The vanilla js way is:

Array.from(new Set(array.map(el => el.name)))
    .map(name => ({
        name,
        value: Array.from(new Set(array.filter(el => el.name === name).flatMap(el => el.value)))
    }))

Example:

const array = [
  {
  name: "foo1",
  value: ["val1","val2"]
}, 
{
  name: "foo1",
  value: ["val2", "val3"]
}, 
{
  name: "foo2",
  value: ["val4"]
},
 {
  name: "foo2",
  value: ["val4","val5"]
},
];

console.log(Array.from(new Set(array.map(el => el.name)))
.map(name => ({
    name,
    value: Array.from(new Set(array.filter(el => el.name === name).flatMap(el => el.value)))
})));

Using lodash you can reduce it to

_.uniq(array.map(el => el.name))
    .map(name => ({
        name,
        value: _.uniq(array.filter(el => el.name === name).flatMap(el => el.value))
    }))

Example:

const array = [
  {
  name: "foo1",
  value: ["val1","val2"]
}, 
{
  name: "foo1",
  value: ["val2", "val3"]
}, 
{
  name: "foo2",
  value: ["val4"]
},
 {
  name: "foo2",
  value: ["val4","val5"]
},
];

console.log(_.uniq(array.map(el => el.name))
    .map(name => ({
        name,
        value: _.uniq(array.filter(el => el.name === name).flatMap(el => el.value))
    })));

<script src="https://cdn.jsdelivr.net/npm/[email protected]/lodash.min.js"></script>

Arpan · Accepted Answer · 2021-01-07 19:38:42Z

Find unique values of keys. Match this keys within array and return unique objects. Push this objects in an empty array. Then match other objects value with the new arrays objects value and push the unmatched values to this new array.

var arr = [
                {
                name: "foo1",
                value: ["val1","val2"]
              }, 
              {
                name: "foo1",
                value: ["val2", "val3"]
              }, 
              {
                name: "foo2",
                value: ["val4"]
              },
               {
                name: "foo2",
                value: ["val4","val5"]
              },
];

let key = [];
arr.map((val)=>key.push(val.name));
let uniquekeys = [...new Set(key)]; //unique values of keys

let newarr = [];
uniquekeys.map((uniquekey,ind)=>{

        let reduceunique = arr.filter((vals)=>uniquekey == vals.name);   // return matching objects as array     
        newarr.push(reduceunique[0]); // Push unique objects in an empty array
        
        for(let i = 1; i<uniquekeys.length;i++){ 
                reduceunique[i].value.map((val)=>{
                        let existvalue = newarr[ind].value.indexOf(val); // Match every value with the unique objects values
                                if(existvalue<0){
                                        newarr[ind].value.push(val); // push the unmatched value in the array
                                }
                });
        };
});
console.log(newarr);

Molham Al Nasr · Accepted Answer · 2021-01-07 10:31:55Z

0

try to use Array.reduce and Array.filter to get the result like the following

var array = [
  {
  name: "foo1",
  value: ["val1","val2"]
}, 
{
  name: "foo1",
  value: ["val2", "val3"]
}, 
{
  name: "foo2",
  value: ["val4"]
},
 {
  name: "foo2",
  value: ["val4","val5"]
},
];

res = array.reduce((prev, curr) => {
  let index = prev.findIndex(item => item.name === curr.name);
 
  if(index > -1) {
    
    prev[index].value = [...prev[index].value, ...curr.value];
    prev[index].value = prev[index].value.filter((v,i) => prev[index].value.indexOf(v) === i)
  } else {
    prev.push(curr);
  }
  return prev;
},[]);

console.log(res);

answered Jan 7, 2021 at 10:31

Molham Al Nasr

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