count by value in array of objects in javascript using lodash

Question

I have an array of objects as follows:

var input_array = [{
    role_name: 'Full Stack Developer',
    position_id: 'b0f00e68-5adc-4209-aec2-9c4962550ab1',
    email_address: '[email protected]',
    application_id: '1dd45634-c283-4a96-a28a-d8a63c418329',
    state: 'qualified',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Delivery Representative',
    position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0',
    email_address: '[email protected]',
    application_id: 'aa7fe2dd-b141-4c64-8350-a1d57bfaa502',
    state: 'interview',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Delivery Representative',
    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',
    email_address: '[email protected]',
    application_id: '166da0ac-aaf1-400d-9a62-e37962f66653',
    state: 'interview',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Delivery Representative',
    position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0',
    email_address: '[email protected]',
    application_id: 'da09a617-8e82-43c0-b1ea-725110a2c4cb',
    state: 'interview',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Delivery Representative',
    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',
    email_address: '[email protected]',
    application_id: '1d55a51a-ecd1-43ea-9cf4-fed101dbebda',
    state: 'offer',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Micro Space Planner',
    position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b',
    email_address: '[email protected]',
    application_id: '293bd084-64f0-4c83-9b5d-aa304e44f066',
    state: 'screening',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Delivery Representative',
    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',
    email_address: '[email protected]',
    application_id: '2adc5236-989d-49f2-ab3e-cb7e42798b77',
    state: 'qualified',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Micro Space Planner',
    position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b',
    email_address: '[email protected]',
    application_id: '293bd084-64f0-4c83-9b5d-aa304e44f066',
    state: 'screening',
    closing_date: '2018-10-28 06:30:00' },
{
    role_name: 'Delivery Representative',
    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',
    email_address: '[email protected]',
    application_id: '2adc5236-989d-49f2-ab3e-cb7e42798b77',
    state: 'qualified',
    closing_date: '2018-10-28 06:30:00' }]

I want to count the object with the state as offer and interview corresponding to each and every position. I am using npm lodash library.

I have checked a few questions on SO about the group by and count using the filter but in my case position id is dynamic. So I can not set the specific value of position_id using which I can group the objects.

e.g. position_id as '12345678-5adc-4209-aec2-8b3962550ce7' contains 1 offer and 1 interview

Expected Output:

{
    role_name: 'Delivery Representative',
    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',
    email_address: '[email protected]',
    offer_count: 1,
    interview_count: 1
},
{
    role_name: 'Micro Space Planner',
    position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b',
    email_address: '[email protected]',
    offer_count: 0,
    interview_count:0
},
{
    role_name: 'Delivery Representative',
    position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0',
    email_address: '[email protected]',
    offer_count: 0,
    interview_count:2
}

So the second code sample is your expected output?

Jared Smith
– Jared Smith

2018-10-25 12:23:33 +00:00
Commented Oct 25, 2018 at 12:23 — Jared Smith
– Jared Smith, Commented Oct 25, 2018 at 12:23
yes, second is for expected output

Deep Kakkar
– Deep Kakkar

2018-10-25 12:24:06 +00:00
Commented Oct 25, 2018 at 12:24 — Deep Kakkar
– Deep Kakkar, Commented Oct 25, 2018 at 12:24

Ele · Accepted Answer · 2018-10-25 12:45:59Z

You can use the function reduce to group the objects by id and the function Object.values to extract the grouped objects.

let input_array = [{    role_name: 'Full Stack Developer',    position_id: 'b0f00e68-5adc-4209-aec2-9c4962550ab1',    email_address: '[email protected]',    application_id: '1dd45634-c283-4a96-a28a-d8a63c418329',    state: 'qualified',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Delivery Representative',    position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0',    email_address: '[email protected]',    application_id: 'aa7fe2dd-b141-4c64-8350-a1d57bfaa502',    state: 'interview',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Delivery Representative',    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',    email_address: '[email protected]',    application_id: '166da0ac-aaf1-400d-9a62-e37962f66653',    state: 'interview',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Delivery Representative',    position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0',    email_address: '[email protected]',    application_id: 'da09a617-8e82-43c0-b1ea-725110a2c4cb',    state: 'interview',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Delivery Representative',    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',    email_address: '[email protected]',    application_id: '1d55a51a-ecd1-43ea-9cf4-fed101dbebda',    state: 'offer',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Micro Space Planner',    position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b',    email_address: '[email protected]',    application_id: '293bd084-64f0-4c83-9b5d-aa304e44f066',    state: 'screening',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Delivery Representative',    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',    email_address: '[email protected]',    application_id: '2adc5236-989d-49f2-ab3e-cb7e42798b77',    state: 'qualified',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Micro Space Planner',    position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b',    email_address: '[email protected]',    application_id: '293bd084-64f0-4c83-9b5d-aa304e44f066',    state: 'screening',    closing_date: '2018-10-28 06:30:00' },{    role_name: 'Delivery Representative',    position_id: '12345678-5adc-4209-aec2-9c4962550ab1',    email_address: '[email protected]',    application_id: '2adc5236-989d-49f2-ab3e-cb7e42798b77',    state: 'qualified',    closing_date: '2018-10-28 06:30:00' }],
    result = Object.values(input_array.reduce((a, {state, role_name, position_id, email_address}) => { 
      a[position_id] = (a[position_id] || {role_name, position_id, email_address, offer_count: 0, interview_count: 0});
      a[position_id].offer_count += (state === 'offer');
      a[position_id].interview_count += (state === 'interview');
      return a;
    }, Object.create(null)));

console.log(result);

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

Rodik · Accepted Answer · 2018-10-25 12:29:28Z

1

You can reduce the original array into a new hash object to hold a map of the positions and count the states of the input array.

let interviews = input_array.reduce(function(acc, cur) {  // go over every applicant
    if (!acc[cur.position_id]) {
        acc[cur.position_id] = {      //set initial object if the job is new
            role_name: cur.role_name,
            ...,
            offer_count: 0,
            interview_count:0
        }
    }

    if (cur.state === "offer") {
        acc[cur.position_id].offer_count++;
    } else if (cur.state === "interview") {
        acc[cur.position_id].interview_count++;
    }

    return acc;
}, {});

Reduce is a native JS array method, so you actually don't need to use lodash or any external libraries for this computation

edited Oct 25, 2018 at 12:29

answered Oct 25, 2018 at 12:28

Rodik

4,10228 silver badges49 bronze badges

2 Comments

Jared Smith Over a year ago

Does not conform to desired output.

Rodik Over a year ago

That is correct, although you can easily transform a hash object into an array using arr = Object.values(obj), i'd still recommend keeping the hash format as it is a better way to store a list of unique job_ids. more easily accessible.

Jared Smith · Accepted Answer · 2018-10-25 12:36:59Z

1

You can use a combination of reduce and map, either the native JS or lodash versions. First, reduce bins up the records by position id, then you map over the object entries to produce the array you want.

Object.entries(input_arr.reduce((acc, item) => {
  if (!acc[item.position_id]) {
    acc[item.position_id] = {
      interview_count: 0,
      offer_count: 0,
      email_address: item.email_address,
      role_name: item.role_name
    };
  }

  if (item.state === 'interview') acc[item.position_id].interview_count += 1;
  if (item.state === 'offer') acc[item.position_id].offer_count += 1;
  return acc;
}, {})).map(([position_id, {email_address, interview_count, offer_count, role_name}]) => {
  return {
    position_id,
    email_address,
    interview_count,
    offer_count,
    role_name
  };
});

Here's a fiddle

edited Oct 25, 2018 at 12:36

answered Oct 25, 2018 at 12:28

Jared Smith

22.3k5 gold badges50 silver badges98 bronze badges

5 Comments

Deep Kakkar Over a year ago

Is variable arr stands for input_array? and what is Object.entries there? and Will the complete code be in a function and I have to call the function using parameters as input_array ? can you please modify the code accordingly?

Jared Smith Over a year ago

@Deep yes to the first question. MDN entry on Object.entries

Deep Kakkar Over a year ago

I appreciate if you please can make jsfiddle for this problem

Jared Smith Over a year ago

@Deep done. See my updated answer. You can run it and inspect the result array in the console.

Deep Kakkar Over a year ago

Ok, I will check. Thank you for your efforts.

Akrion · Accepted Answer · 2018-11-08 05:54:41Z

You can do this with something like this without lodash and via reduce, Object.assign & Object.values:

var data = [{ role_name: 'Full Stack Developer', position_id: 'b0f00e68-5adc-4209-aec2-9c4962550ab1', email_address: '[email protected]', application_id: '1dd45634-c283-4a96-a28a-d8a63c418329', state: 'qualified', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Delivery Representative', position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0', email_address: '[email protected]', application_id: 'aa7fe2dd-b141-4c64-8350-a1d57bfaa502', state: 'interview', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Delivery Representative', position_id: '12345678-5adc-4209-aec2-9c4962550ab1', email_address: '[email protected]', application_id: '166da0ac-aaf1-400d-9a62-e37962f66653', state: 'interview', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Delivery Representative', position_id: '090276f0-3fca-4b2a-85ed-697d21c405a0', email_address: '[email protected]', application_id: 'da09a617-8e82-43c0-b1ea-725110a2c4cb', state: 'interview', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Delivery Representative', position_id: '12345678-5adc-4209-aec2-9c4962550ab1', email_address: '[email protected]', application_id: '1d55a51a-ecd1-43ea-9cf4-fed101dbebda', state: 'offer', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Micro Space Planner', position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b', email_address: '[email protected]', application_id: '293bd084-64f0-4c83-9b5d-aa304e44f066', state: 'screening', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Delivery Representative', position_id: '12345678-5adc-4209-aec2-9c4962550ab1', email_address: '[email protected]', application_id: '2adc5236-989d-49f2-ab3e-cb7e42798b77', state: 'qualified', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Micro Space Planner', position_id: 'fe30930f-7d9f-4953-8939-6d9924462b2b', email_address: '[email protected]', application_id: '293bd084-64f0-4c83-9b5d-aa304e44f066', state: 'screening', closing_date: '2018-10-28 06:30:00' }, { role_name: 'Delivery Representative', position_id: '12345678-5adc-4209-aec2-9c4962550ab1', email_address: '[email protected]', application_id: '2adc5236-989d-49f2-ab3e-cb7e42798b77', state: 'qualified', closing_date: '2018-10-28 06:30:00' }]

const combine = (r = {offer_count: 0, interview_count: 0}, c) => {
   r.offer_count += c.state ==='offer'
   r.interview_count += c.state === 'interview'
   let {application_id, state, closing_date, ...rest} = c
   return Object.assign(r, rest)
}
const countEm = d => Object.values(d.reduce((r,c) => (r[c.position_id] = combine(r[c.position_id], c), r), {}))

console.log(countEm(data))

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