We Keep Coding

Using Javascript 2D array duplicate record in one row by adding one property value with final array only unique record with modified properties

Question Array:
let array=[
["a23","3000","0","ES08"],
["a23","3000","0","ES93"],
["a23","3000","0","ES71"],
["12w","3007","0","ES34"],
["12w","3007","0","ES56"],
["1v8","3008","0","ES08"]
]
Condition:
Duplicate record constraints array[0][0]+array[0][1] equal to array[1][0]+array[1][1].....etc
Expected Result:
array= [
["a23","3000","0","ES08ES93ES71"],
["12w","3007","0","ES34ES56"],
["1v8","3008","0","ES08"]
]

Simple approach would be :
Group elements and accumulate last element (which contains different ES*) in an array:
{ "a2330000": [["ES08"], ["ES93"], ["ES71"]], "12w30070": [["ES34"], ["ES56"]], "1v830080": [["ES08"]], }
Loop again to get those accumulated ES* and join them back.
let array=[ ["a23","3000","0","ES08"], ["a23","3000","0","ES93"], ["a23","3000","0","ES71"], ["12w","3007","0","ES34"], ["12w","3007","0","ES56"], ["1v8","3008","0","ES08"] ];
let obj = {}
for (let arr of array) {
let key = arr.slice(0,-1).join('');
obj[key]??= [];
obj[key].push(arr.slice(-1));
}
let output = []
for (let arr of array) {
let key = arr.slice(0,-1).join('');
if(obj[key] && !obj[key].visited){
output.push([...arr.slice(0,-1),obj[key].join('')])
obj[key].visited = true;
}
}
console.log(output)
Note: I added visited property just to not create duplicate inner arrays of the same id key (combination of three first element of inner array)

Convert Array of arrays of objects to Array of Arrays

I have to following array:
var arr1 = [
[{n:"0.1",m:"m.0",other:"eg1"}],
[{n:"1.1",m:"m.1",other:"eg2"}],
[{n:"2.1",m:"m.2",other:"eg3"}]
];
And I would like to convert it to an array of arrays, as follows:
var arr1 = [
["0.1","0"],
["1.1","1"],
["2.1","2"]
];
I would like to convert to the other array only a few properties, not all of them.
Any idea how I can do this?
PS: I was using flatMap from another post but it does not work as it does not exist in Edge.

Assuming that the second value in each subarray is coming from the number after the period from the m key, you could use the map function to accomplish this:
var arr1 = [
[{n:"0.1",m:"m.0",other:"eg1"}],
[{n:"1.1",m:"m.1",other:"eg2"}],
[{n:"2.1",m:"m.2",other:"eg3"}]
];
var newArray = arr1.map(x => [x[0].n, x[0].m.split('.')[1]]);
console.log(newArray);

For next time you have to put your attempts.
this is the solution for your problem
var arr1 = [
[{n:"0.1",m:"m.0",other:"eg1"}],
[{n:"1.1",m:"m.1",other:"eg2"}],
[{n:"2.1",m:"m.2",other:"eg3"}]
];
arr1 = arr1.map(currentArray=>{
const item = currentArray.shift();
return [item.n,item.m.replace( /^\D+/g, '')]
});

How to group multiple sets of duplicate integers in an array into their own array of arrays?

I am trying to split an array of integers into an array of arrays by duplicate values. The original array is composed of a list of 6 digit integers, some of these integers come in pairs, others come in groups of 3 or 4s. I'd like to get these duplicates pushed to their own arrays and have all of these arrays of duplicates composed into an array of arrays that I can later loop through.
I've looked on in the lodash library for some method or combination of but can't quite find anything that seems to work. I've also tried a few different configurations with nested for loops but also am struggling with that.
const directory = "X/";
let files = fs.readdirSync(directory);
let first6Array = [ ];
for(i=0; i< files.length; i++){
let first6 = files[i].substring(0, 6);
first6Array.push(first6);
};
console.log(first6Array);
example output of first6Array:
[ '141848',
'141848',
'141848',
'142851',
'142851',
'143275',
'143275']
I'd like to end up with something like
let MasterArray = [[141848,141848,141848],[142851,142851],[143275,143275]];

You can use new Set() to filter out the duplicates.
Then you use the unique Array and filter for every value.
const firstArray = [ '141848', '141848', '141848', '142851', '142851', '143275', '143275'];
const numberArray = firstArray.map(Number);
const masterArray = [];
const unique = new Set (numberArray); // Set {141848, 142851, 143275}
unique.forEach(u => {
masterArray.push(numberArray.filter(e => e === u));
});
console.log(masterArray);

Using lodash, you can create a function with flow:
map the items by truncating them and converting to numbers.
groupBy the value (the default).
convert to an array of arrays using values.
const { flow, partialRight: pr, map, truncate, groupBy, values } = _;
const truncate6 = s => truncate(s, { length: 6, omission: '' });
const fn = flow(
pr(map, flow(truncate6, Number)),
groupBy,
values,
);
const firstArray = [ '141848abc', '141848efg', '141848hij', '142851klm', '142851opq', '143275rst', '143275uvw'];
const result = fn(firstArray);
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

Use reduce to create an object of arrays, indexed by number, and push to the associated array on each iteration (creating the array at the key first if needed), then get the values of the object:
const directory = "X/";
const files = fs.readdirSync(directory);
const output = Object.values(
files.reduce((a, file) => {
const num = Number(file.slice(0, 6));
if (!a[num]) a[num] = [];
a[num].push(num);
return a;
}, {})
);
It's pretty weird to have an array of identical values, though - you might consider a different data structure like
{
'141848': 3,
'142851': 2
}
to keep track of the number of occurrences of each number:
const output = files.reduce((a, file) => {
const num = file.slice(0, 6);
a[num] = (a[num] || 0) + 1;
return a;
}, {})

To obtain exactly the result you desire, you need a nested find, something like this should works:
const directory = "X/";
let files = fs.readdirSync(directory);
let first6Array = files.reduce((acc, value)=> {
let n = +value.substr(0, 6); // assumes it can't be NaN
let arr = acc.find(nested => nested.find(item => item === n));
if (arr) {
arr.push(n);
} else {
acc.push([n]);
}
return acc;
}, []);
console.log(first6Array);
Notice that an hashmap instead, with the value and the number of occurrence, would be better, also in term of performance, but I don't think it mind since you have really few elements.
Also, it assumes the first six characters are actually numbers, otherwise the conversion would fail and you'll get NaN.
It would be safer adding a check to skip this scenario:
let n = +value.substr(0, 6);
if (isNaN(n)) {
return acc;
}
// etc

Compare arrays of objects independent of the order

I have 2 arrays of objects and I have to compare them, but the order of the objects DOES NOT matter. I can't sort them because I won't have their keys' names because the functions must be generic. The only information that I'll have about the array is that both array's objects have the same amount of keys and those keys have the same name. So the array1 must contain the same objects as the array2.
var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
In the example, array1 must be equal array2.
I tryed to use the chai .eql() method but it didn't work.

The following solution:
will verify that the arrays have an equal number of elements
does not impose restrictions on keys (as to not contain a certain delimiter)
requires both keys and (string) values to be the same
has a time complexity of O(nlogn) (instead of O(n²) as some other solutions here)
function equalArrays(a, b) {
if (a.length !== b.length) return false;
const ser = o => JSON.stringify(Object.keys(o).sort().map( k => [k, o[k]] ));
a = new Set(a.map(ser));
return b.every( o => a.has(ser(o)) );
}
// Example
var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
console.log(equalArrays(array1, array2)); // true
// Example with different key name
var array1 = [{"key0":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
console.log(equalArrays(array1, array2)); // false

You can array#join each value of the object on an separator and then generate a new array of string and then compare each values using array#every and array#includes
var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
values = (o) => Object.keys(o).sort().map(k => o[k]).join('|'),
mapped1 = array1.map(o => values(o)),
mapped2 = array2.map(o => values(o));
var res = mapped1.every(v => mapped2.includes(v));
console.log(res);

You can do something like following:
For each object in each array you can calc its representation:
arr1.forEach( (obj) => {
obj.representation = '';
for (let key of Object.keys(obj)) {
obj.representation += obj[key];
}
}
Same for arr2
now you can sort both arrays by representation for example and then compare.
To sort do the following:
arr1.sort( (a,b) => { return a.representation > b.representation } );
arr2.sort( (a,b) => { return a.representation > b.representation } );
After sorting you can compare both arrays
let equal = arr1.every( (el, i) => arr2[i]===el );

When to use object and when array

I have an situation where I have 3 different arrays with very different amounts of objects in it. I've read many questions and blog posts about this but Im still unsure when to use what.
PS! My biggest problem is that I need to iterate and push (perfect for arrays), also find if exists in array and delete (more suitable for objects). Specific order is not required.
I can't allow having same object in both array1 and array1clicked
because they should perform different actions.
When it's best to use object and when array in my example? What should I replace with object and what should stay as array? Im pretty sure that amounts of objects in it also matters, right?
My current code:
//Objects in arrays are literally custom {objects} with custom prototypes and html
var array1 = [ 20 objects ];
var array1clicked = [];
var array2 = [ 250 objects ];
var array2clicked = [];
var array3 = [ 50 000 objects ];
var array3clicked = [];
//Each object in arrays has event attached
objecthtml.click(function() {
//Add to clicked array
array1clicked.push(thisobject);
//Remove from initial array
var index = array1.indexOf(thisobject);
if (index > -1) {
array1.splice(index, 1);
}
}
//Same with array2 and array3 objects
//Iterations on different conditions
var array1count = array1.length;
var array1clickedcount = array1clicked.length;
//Same with array2 and array3
if(condition1) {
for(a = 0; a < array1count; a++) {
array1[a].div.style.visibility = 'hidden';
}
//Same with array2 and array3 objects
for(a = 0; a < array1clickedcount; a++) {
array1clicked[a].div.style.visibility = 'visible';
}
//Same with array2clicked and array3clicked objects
}
else if(condition2) {
for(a = 0; a < array1count; a++) {
array1[a].div.style.visibility = 'visible';
}
//Same with array2 and array3 objects
for(a = 0; a < array1clickedcount; a++) {
array1clicked[a].div.style.visibility = 'hidden';
}
//Same with array2clicked and array3clicked objects
}

It seems you want a data structure with these operations:
Iteration
Insert
Delete
Search
With arrays, the problem is that searches and deletions (with reindexing) are slow.
With objects, the problem is that the property names can only be strings.
The perfect structure is a set.
var s = new Set();
s.add(123); // insert
s.has(123); // search
s.delete(123); // delete
s.values(); // iterator

In your case, I think you have to use just Array.
In common case, you could use object to keep references and push some values into it, but If you wanna iterate on this, I think you have to use Array.