Providing an aggregate outcome from an array

Question

Providing an aggregate outcome from an array

There's a puzzle for you:

data = [ '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]' ]

I've tried my best to solve it, but still can't figure out how to achieve this specific format:

2016-12-12 pass:2 fail: 1
2016-12-13 pass:0 fail: 1
2016-12-14 pass:2 fail: 1
2016-12-15 pass:1 fail: 0
2016-12-16 pass:0 fail: 1

javascript arrays

Answer 1

Answer №1

Here is a method to achieve the desired outcome:

const info = [
  '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]',
];

const tally = {};

info.forEach(entry => {
  const [date, status] = entry.split(' ');
  
  if (!(date in tally)) {
    tally[date] = { pass: 0, fail: 0 };
  }
  
  tally[date][status] += 1;
});

console.log(tally);

The above code will generate an object with dates as property names and objects containing pass and fail counts as values.

Keep in mind that using reduce instead of forEach could reduce redundancy, but for simplicity in this case, forEach was used.

Additionally, JavaScript object properties are technically unordered, even though they may retain their insertion order in most cases. For strict ordering, consider transforming the object into an array after the fact like so:

const result = {
  "2016-12-12": { pass: 2, fail: 1 },
  "2016-12-13": { pass: 0, fail: 1 },
  "2016-12-14": { pass: 2, fail: 1 },
  "2016-12-15": { pass: 1, fail: 0 },
  "2016-12-16": { pass: 0, fail: 1 },
};

const resultArray = Object.keys(result).sort()
                      .map(key => [ key, result[key] ]);

console.log(resultArray);

Answer 2

Here is a method to achieve the desired outcome:

const info = [
  '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]',
];

const tally = {};

info.forEach(entry => {
  const [date, status] = entry.split(' ');
  
  if (!(date in tally)) {
    tally[date] = { pass: 0, fail: 0 };
  }
  
  tally[date][status] += 1;
});

console.log(tally);

The above code will generate an object with dates as property names and objects containing pass and fail counts as values.

Keep in mind that using reduce instead of forEach could reduce redundancy, but for simplicity in this case, forEach was used.

Additionally, JavaScript object properties are technically unordered, even though they may retain their insertion order in most cases. For strict ordering, consider transforming the object into an array after the fact like so:

const result = {
  "2016-12-12": { pass: 2, fail: 1 },
  "2016-12-13": { pass: 0, fail: 1 },
  "2016-12-14": { pass: 2, fail: 1 },
  "2016-12-15": { pass: 1, fail: 0 },
  "2016-12-16": { pass: 0, fail: 1 },
};

const resultArray = Object.keys(result).sort()
                      .map(key => [ key, result[key] ]);

console.log(resultArray);

Answer 3

Answer №2

If you want to transform an array of strings into an array of objects, you can achieve this using the reduce() method.

var data = [ '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]' ]
  
var result = Object.values(data.reduce(function(accumulator, current) {
  var arr = current.split(' ')
  if(!accumulator[arr[0]]) accumulator[arr[0]] = {date: arr[0], pass: 0, fail: 0} 
  accumulator[arr[0]][arr[1]]++
  return accumulator;
}, {}))

console.log(JSON.stringify(result))

If your environment doesn't support Object.values(), you can use map on the object after the reduce operation.

var data = [ '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]' ]
  
var result = data.reduce(function(accumulator, current) {
  var arr = current.split(' ')
  if(!accumulator[arr[0]]) accumulator[arr[0]] = {date: arr[0], pass: 0, fail: 0} 
  accumulator[arr[0]][arr[1]]++
  return accumulator;
}, {})

result = Object.keys(result).map(e => result[e])

console.log(JSON.stringify(result))

Answer 4

If you want to transform an array of strings into an array of objects, you can achieve this using the reduce() method.

var data = [ '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]' ]
  
var result = Object.values(data.reduce(function(accumulator, current) {
  var arr = current.split(' ')
  if(!accumulator[arr[0]]) accumulator[arr[0]] = {date: arr[0], pass: 0, fail: 0} 
  accumulator[arr[0]][arr[1]]++
  return accumulator;
}, {}))

console.log(JSON.stringify(result))

If your environment doesn't support Object.values(), you can use map on the object after the reduce operation.

var data = [ '2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]' ]
  
var result = data.reduce(function(accumulator, current) {
  var arr = current.split(' ')
  if(!accumulator[arr[0]]) accumulator[arr[0]] = {date: arr[0], pass: 0, fail: 0} 
  accumulator[arr[0]][arr[1]]++
  return accumulator;
}, {})

result = Object.keys(result).map(e => result[e])

console.log(JSON.stringify(result))

Answer 5

Answer №3

To achieve a grouped hash of dates, you can utilize the reduce method. The resulting output will be an object nested within another object.

function groupDates(arr) {
  return arr.reduce(function(hash, e) {  
    var parts = e.split(' ');                
    if(hash[parts[0]]) {                     
      hash[parts[0]][parts[1]]++;            
    }
    else {                                   
      hash[parts[0]] = {pass: 0, fail: 0};   
      hash[parts[0]][parts[1]]++;            
    }
    return hash;
  }, {});
}

var dateArray = ['2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]'
];

console.log(groupDates(dateArray));

Answer 6

To achieve a grouped hash of dates, you can utilize the reduce method. The resulting output will be an object nested within another object.

function groupDates(arr) {
  return arr.reduce(function(hash, e) {  
    var parts = e.split(' ');                
    if(hash[parts[0]]) {                     
      hash[parts[0]][parts[1]]++;            
    }
    else {                                   
      hash[parts[0]] = {pass: 0, fail: 0};   
      hash[parts[0]][parts[1]]++;            
    }
    return hash;
  }, {});
}

var dateArray = ['2016-12-12 pass [pass]',
  '2016-12-12 pass [pass]',
  '2016-12-12 fail [fail]',
  '2016-12-13 fail [fail]',
  '2016-12-14 fail [fail]',
  '2016-12-14 pass [pass]',
  '2016-12-14 pass [pass]',
  '2016-12-15 pass [pass]',
  '2016-12-16 fail [fail]'
];

console.log(groupDates(dateArray));

Providing an aggregate outcome from an array

Answer №1

Answer №2

Answer №3

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