Generating a distinct datetime string value from an array of nested arrays using JavaScript

I'm facing a challenge where I need to iterate over an array of arrays structure to filter out duplicate datetime string values and then store the unique datetime string values in a new array while ensuring they are sorted. My attempt at using a nested forEach() method failed as it wasn't working as expected.

This is the array of arrays structure:

arr =[
   ["some_value", "2016-11-23 18:11", 1]
   ["some_value", "2016-11-23 18:01", 1]
   ["some_value", "2016-11-23 18:01", 2]
   ["some_value", "2016-11-23 18:01", 1]
   ["some_value", "2016-11-23 18:22", 1]
   ["some_value", "2016-11-23 18:23", 1]
   ["some_value", "2016-11-23 18:25", 1]
   ["some_value", "2016-11-23 18:24", 3]
   ["some_value", "2016-11-23 18:26", 1]
   ["some_value", "2016-11-23 18:27", 1]
];

The desired result:

res = ["2016-11-23 18:01",
       "2016-11-23 18:11", 
       "2016-11-23 18:22",
       "2016-11-23 18:23",
       "2016-11-23 18:24",
       "2016-11-23 18:25",
       "2016-11-23 18:26",
       "2016-11-23 18:27"];

I would appreciate any guidance or tips on how to approach this issue effectively.

javascriptarrays

Answer №1

To simplify the array of arrays and extract just an array of date strings, you can use the following code:

arr = arrayOfArrays.map(x => x[1])

If you convert this array to a set, you will obtain unique values:

var set = new Set(arr)

If necessary, you can then transform it back into an array:

var uniq = Array.from(set)

For sorting purposes:

uniq.sort((a,b)=> new Date(a) - new Date(b))


var arrayOfArrays = [
   ["some_value", "2016-11-23 18:11", 1],
   ["some_value", "2016-11-23 18:01", 1],
   ["some_value", "2016-11-23 18:01", 2],
   ["some_value", "2016-11-23 18:01", 1],
   ["some_value", "2016-11-23 18:22", 1],
   ["some_value", "2016-11-23 18:23", 1],
   ["some_value", "2016-11-23 18:25", 1],
   ["some_value", "2016-11-23 18:24", 3],
   ["some_value", "2016-11-23 18:26", 1],
   ["some_value", "2016-11-23 18:27", 1],
];

var arr = arrayOfArrays.map(x => x[1])
var set = new Set(arr)

var uniq = Array.from(set)

uniq.sort((a,b)=> new Date(a) - new Date(b))

console.log(uniq)

Answer №2

Using map and Set for Extraction

To extract dates from the array, you can utilize the map function:

const extractedDates = arr.map(data => data[1]);

Subsequently, by storing these dates in a new Set, which retains unique values within an array. By invoking .values on this set, you can retrieve its distinct elements.

arr = [
   ["some_value", "2016-11-23 18:11", 1],
   ["some_value", "2016-11-23 18:01", 1],
   ["some_value", "2016-11-23 18:01", 2],
   ["some_value", "2016-11-23 18:01", 1],
   ["some_value", "2016-11-23 18:22", 1],
   ["some_value", "2016-11-23 18:23", 1],
   ["some_value", "2016-11-23 18:25", 1],
   ["some_value", "2016-11-23 18:24", 3],
   ["some_value", "2016-11-23 18:26", 1],
   ["some_value", "2016-11-23 18:27", 1],
];


const extractedDates = arr.map(item => item[1]);
const uniqueResults = new Set(extractedDates);

console.log('uniqueResults: ', Array.from(uniqueResults))

Expand Your Knowledge!

If you want to delve deeper into sets, take a look at more information here on MDN

An illustration illustrating the concept of functional style using array functions like map/filter/reduce with a hint of humor (assuming onions are excluded during 'filter'):

https://i.sstatic.net/hwkvV.png

Image Source: https://twitter.com/francesc/status/507942534388011008

Answer №3

Utilizing the power of lodash, I find solutions to my coding challenges. The relevance of this tool continues to impress me.

let data =[
    ["value_A", "2016-11-23 18:11", 1],
    ["value_B", "2016-11-23 18:01", 1],
    ["value_C", "2016-11-23 18:01", 2],
    ["value_D", "2016-11-23 18:01", 1],
    ["value_E", "2016-11-23 18:22", 1],
    ["value_F", "2016-11-23 18:23", 1],
    ["value_G", "2016-11-23 18:25", 1],
    ["value_H", "2016-11-23 18:24", 3],
    ["value_I", "2016-11-23 18:26", 1],
    ["value_J", "2016-11-23 18:27", 1]
];

_.map(_.sortBy(_.uniqBy(data, n => n[1]), n => n[1]), n => n[1]);

Answer №4

        const data = data = [
        ["value_1", "2021-10-15 09:30", 1],
        ["value_2", "2021-10-15 10:00", 1],
        ["value_3", "2021-10-15 10:00", 2],
        ["value_4", "2021-10-15 10:00", 1],
        ["value_5", "2021-10-15 10:30", 1],
        ["value_6", "2021-10-15 10:45", 1],
        ["value_7", "2021-10-15 10:50", 1],
        ["value_8", "2021-10-15 10:48", 3],
        ["value_9", "2021-10-15 10:55", 1],
        ["value_10", "2021-10-15 11:00", 1],
     ];
    const datesData = data.map(item => item[1])
    const uniqueDatesArray = datesData.filter(function (element, index) {
        return datesData.indexOf(element) == index;
    });

Answer №5

If you're looking to achieve a specific result, consider implementing the following code:


function onlyUnique(value, index, self) { 
  return self.indexOf(value) === index;
}

var arr =[
  ["some_value", "2016-11-23 18:11", 1],
  ["some_value", "2016-11-23 18:01", 1],
  ["some_value", "2016-11-23 18:01", 2],
  ["some_value", "2016-11-23 18:01", 1],
  ["some_value", "2016-11-23 18:22", 1],
  ["some_value", "2016-11-23 18:23", 1],
  ["some_value", "2016-11-23 18:25", 1],
  ["some_value", "2016-11-23 18:24", 3],
  ["some_value", "2016-11-23 18:26", 1],
  ["some_value", "2016-11-23 18:27", 1]
];

var rest = [];


arr.forEach(function(entry) {

rest.push(entry[1]) 
});

rest.sort();

var finalArr = rest.filter( onlyUnique );

console.log(finalArr);

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