Filtering and sorting a JSON array

Question

records = [
        {
            name: "Alpha",
            set: 5,
            weight: 185
        },      
        {
            name: "Alpha",
            set: 5,
            weight: 350
        },        
        {
            name: "Bravo",
            set: 5,
            weight: 185
        },        
        {
            name: "Charlie",
            set: 5,
            weight: 185
        },         
        {
            name: "Delta",
            set: 5,
            weight: 185
        }
]

I have a JSON array of multiple records and I need to filter these records by name and weight. So for example, since there are two "Alpha" records, I need to only pull in the one with the highest weight (which would be the second record). I have no idea how to filter and rebuild this array with only the desired results.

I need to keep the original array intact as I'll be displaying ALL in a table, but I need to build a secondary array with only the objects with the greatest value, by name.

Refer this similar Question : stackoverflow.com/a/17037756/6449750 — Hardik Vaghani
– Hardik Vaghani, Commented Mar 21, 2017 at 5:04

Akhil Menon · Accepted Answer · 2017-03-21 05:44:01Z

4

You can use lodash 4+ for this.

var sortedArray = _.orderBy(records, ['weight'], ['desc']);

This will sort the array by weight. Then , _.uniqBy(sortedArray,'name')

This will return the final array.

var records = [
        {
            name: "Alpha",
            set: 5,
            weight: 185
        },      
        {
            name: "Alpha",
            set: 5,
            weight: 350
        },        
        {
            name: "Bravo",
            set: 5,
            weight: 185
        },        
        {
            name: "Charlie",
            set: 5,
            weight: 185
        },         
        {
            name: "Delta",
            set: 5,
            weight: 185
        }
]

var sortedArray = _.orderBy(records, ['weight'], ['desc'])

_.uniqBy(sortedArray,'name')

answered Mar 21, 2017 at 5:44

Akhil Menon

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Comments

nb1987 · Accepted Answer · 2017-03-21 05:37:08Z

3

I recommend a functional programming approach:

var newRecords = records
    .filter(function(record) { 
        return records.find(function(innerRecord) {
            return innerRecord.name === record.name && innerRecord.weight > record.weight; }) === undefined;
     });

In this example, you return only records where you cannot find a record sharing the same name but with a larger weight. Also, your newly re-built array is stored in newRecords, leaving your original array intact.

edited Mar 21, 2017 at 5:37

answered Mar 21, 2017 at 5:13

nb1987

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Comments

Alex Pashkin · Accepted Answer · 2017-03-21 05:37:22Z

2

I recommend you start using lodash and dont spend time to create your own functions. For example, to sort your array by name you should write the following code:

    var records = [
        {
            name: "Alpha",
            set: 5,
            weight: 185
        },      
        {
            name: "Alpha",
            set: 5,
            weight: 350
        },        
        {
            name: "Bravo",
            set: 5,
            weight: 185
        },        
        {
            name: "Charlie",
            set: 5,
            weight: 185
        },         
        {
            name: "Delta",
            set: 5,
            weight: 185
        }
];
var sorted = _.sortBy(records, ['name']);

And second case, to filter by name and weight

var filtered = _.filter(records, [ 'name': 'Alpha', 'weight': 350 ]);

edited Mar 21, 2017 at 5:37

answered Mar 21, 2017 at 5:27

Alex Pashkin

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4 Comments

E. Sundin Over a year ago

Does this also filter out multiple of the same type? As this is something OP wants

Alex Pashkin Over a year ago

And code will look like _.filter(records, [name:"Alpha", weight: 350]

E. Sundin Over a year ago

It should be included in the answer, as of now your solution only solves the sorting.

Alex Pashkin Over a year ago

Updated the solution

E. Sundin · Accepted Answer · 2017-03-21 05:20:23Z

This first sorts the items in name order and weight order and then filter out all but the first of each item.

var records = [{
    name: "Alpha",
    set: 5,
    weight: 185
  },
  {
    name: "Alpha",
    set: 5,
    weight: 350
  },
  {
    name: "Bravo",
    set: 5,
    weight: 185
  },
  {
    name: "Charlie",
    set: 5,
    weight: 185
  },
  {
    name: "Charlie",
    set: 5,
    weight: 200
  },
  {
    name: "Delta",
    set: 5,
    weight: 185
  }
]

console.log(
  records.sort((a, b) => {
    if (a.name === b.name) {
      return a.weight >= b.weight ? -1 : 1
    }
    return a.name > b.name ? 1 : -1
  })
  .filter((rec, i, arr) => {
    if (i === 0) return true
    return rec.name !== arr[i - 1].name
  })
)

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