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Split an array into two Parts [closed]

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How can we split or divide an array into two new arrays?
SingleARR = [7,5,6,4,3,2,4,5,4,2,8,8];
one array should have values that don't repeat
and the other has values that repeat. Moreover, both new arrays should have different elements from each other.

First, count the frequencies. Then filter it by the frequency if it is one then that does not repeat and push it into one array. Then again filter it by the frequency, if it is greater than 1 then it repeats and pushes
let a = [7, 5, 6, 4, 3, 2, 4, 5, 4, 2, 8, 8];
let ret = a.reduce((p, c) => {
if (!p[c]) p[c] = 1;
else p[c] += 1;
return p;
}, {});
let x = [];
let y = [];
console.log(ret);
for (prop in ret) if (ret[prop] === 1) x.push(+prop);
for (prop in ret) if (ret[prop] > 1) y.push(+prop);
console.log(x);
console.log(y);
it into another array.

Loop multiple lists based on their length [closed]

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In my code I have 6 lists of objects of different sizes.
I need to go through them all in a specific order, from the smallest list to the largest.
var list_1 = [...] // length 24
var list_2 = [...] // length 4
var list_3 = [...] // length 3
var list_4 = [...] // length 4
var list_5 = [...] // length 11
var list_6 = [...] // length 2
// Need code here for loop each list in order asc
list_6.forEach(...) // length 2
list_3.forEach(...) // length 3
list_2.forEach(...) // length 4
list_4.forEach(...) // length 4
list_5.forEach(...) // length 11
list_1.forEach(...) // length 24
Does anyone have a simple solution ? Thanks

You could add the lists in an array, sort it and perform the loop
[list, list2, ...]
.sort((a, b) => a.length - b.length)
.forEach(array => array.forEach(...))

Put the lists into another list and sort them.
const list1 = [1, 2, 3, 4],
list2 = [1],
list3 = [1, 2, 3, 4, 5, 6, 7];
let listOfLists = [list1, list2, list3].sort((a, b) => a.length - b.length);
console.log(listOfLists);
listOfLists.forEach(list => {
list.forEach(itemInList => {
console.log(itemInList);
});
});
See StackBlitz example.

How to count the frequencies of elements in an array [closed]

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Assuming you have an array x = [1, 1, 2, 2, 2, 3], and you had to output a sorted array of objects containing a key-value pair (where the key represents the element, and the value the frequency) like:
y = [
{
2: 3
},
{
1: 2
},
{
3: 1
}
]
The resulting array should be sorted by the values.
What would be the best way of doing this?

You can create a temporary object and do simple .forEach and check if current number exists in object as key, if true plus 1 to the value, otherwise create that key, then with simple .map add all key value pairs in separate object in new array
const x = [1, 1, 2, 2, 2, 3];
const k = {};
x.forEach(v => {
if(k[v]) {
k[v] +=1;
} else {
k[v] = 1;
}
});
const y = Object.keys(k).sort((t,c) => k[c] - k[t]).map(key => ({[key]: k[key]}));
console.log(y);

Get the top keyword in an array? [closed]

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I have an array like this:
var words = { 'love': 4; 'peace': 10; 'war':3; 'family':13; 'dog':19, 'life':7 };
What is the fastest way to get the top 2 keywords (family and dog in this case) ?

Take the keys and sort them with their values descending and take the first 2 elements.
var words = { 'love': 4, 'peace': 10, 'war': 3, 'family': 13, 'dog': 19, 'life': 7 },
top2 = Object.keys(words).sort(function (a, b) {
return words[b] - words[a];
}).slice(0, 2);
document.write('<pre>' + JSON.stringify(top2, 0, 4) + '</pre>');

Sort array and return an array of indicies that indicates the position of the sorted elements with respect to the original elements (new) [closed]

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I have this array
test = [3, 2, 2, 1];
I want to be able to get this array
result = [3, 1, 2, 0]
The idea is the same as: Javascript: Sort array and return an array of indicies that indicates the position of the sorted elements with respect to the original elements
but incrementing the position value every time there is two elements on "test" with the same value.

You can pass a comparison function to sort:
var test = [3, 2, 2, 1];
var result = [];
for(var i = 0; i != test.length; ++i) result[i] = i;
result = result.sort(function(u,v) { return test[u] - test[v]; })
console.log(result) // [ 3, 1, 2, 0 ]