Get common data from multiple arrays of object that containing a unique id and nested array using javascript es6
After concatenating the arrays, finding the max common hour can be done through a filter that only keeps duplicates, then gets sorted. Once we have that, we can query each array to make sure it contains the max hour, then extract the max date and time. My output was slightly different than yours because i filtered for the max time, hour and date
array1 = [{
_id: "60f027f98b55eb2df1f36c04",
date: "2021-07-15T12:18:12.223Z",
time: "30",
hours: ["8:00 AM", "8:30 AM"]
}]
array2 = [{
_id: "60f027f98b55eb2df1f36c05",
date: "2021-07-15T12:18:12.223Z",
time: "60",
hours: ["7:30 AM", "8:30 AM", "9:30AM"]
}]
array3 = [{
_id: "60f027f98b55eb2df1f36c06",
date: "2021-07-16T12:12:12.223Z",
time: "30",
hours: ["7:00 AM", "8:30 AM"]
}]
const getCommon = (arrays) => {
let group = [].concat.apply([], [...arrays])
let hour = group.map(e=>e.hours).flat().filter((e,i,a) => a.indexOf(e) !== i).sort((a,b) => a.localeCompare(b))[0]
let common = group.filter(e=>e.hours.includes(hour))
let time = Math.max(...common.map(e => +e.time))
let date = common.map(e => e.date).sort((a,b) => new Date(b) - new Date(a))[0];
return {date: date, time: time, hours: [hour]}
}
let arg = []
arg.push(array1)
arg.push(array2)
arg.push(array3)
console.log(getCommon(arg))
How to get the difference between two arrays of objects in JavaScript
Using only native JS, something like this will work:
const a = [{ value:"0", display:"Jamsheer" }, { value:"1", display:"Muhammed" }, { value:"2", display:"Ravi" }, { value:"3", display:"Ajmal" }, { value:"4", display:"Ryan" }];
const b = [{ value:"0", display:"Jamsheer", $$hashKey:"008" }, { value:"1", display:"Muhammed", $$hashKey:"009" }, { value:"2", display:"Ravi", $$hashKey:"00A" }, { value:"3", display:"Ajmal", $$hashKey:"00B" }];
// A comparer used to determine if two entries are equal.
const isSameUser = (a, b) => a.value === b.value && a.display === b.display;
// Get items that only occur in the left array,
// using the compareFunction to determine equality.
const onlyInLeft = (left, right, compareFunction) =>
left.filter(leftValue =>
!right.some(rightValue =>
compareFunction(leftValue, rightValue)));
const onlyInA = onlyInLeft(a, b, isSameUser);
const onlyInB = onlyInLeft(b, a, isSameUser);
const result = [...onlyInA, ...onlyInB];
console.log(result);
Simplest code for array intersection in javascript
Use a combination of Array.prototype.filter
and Array.prototype.includes
:
const filteredArray = array1.filter(value => array2.includes(value));
For older browsers, with Array.prototype.indexOf
and without an arrow function:
var filteredArray = array1.filter(function(n) {
return array2.indexOf(n) !== -1;
});
NB! Both .includes
and .indexOf
internally compares elements in the array by using ===
, so if the array contains objects it will only compare object references (not their content). If you want to specify your own comparison logic, use Array.prototype.some
instead.
Finding matches between multiple JavaScript Arrays
var result = arrays.shift().filter(function(v) {
return arrays.every(function(a) {
return a.indexOf(v) !== -1;
});
});
DEMO: http://jsfiddle.net/nWjcp/2/
You could first sort the outer Array to get the shortest Array at the beginning...
arrays.sort(function(a, b) {
return a.length - b.length;
});
For completeness, here's a solution that deals with duplicates in the Arrays. It uses .reduce()
instead of .filter()
...
var result = arrays.shift().reduce(function(res, v) {
if (res.indexOf(v) === -1 && arrays.every(function(a) {
return a.indexOf(v) !== -1;
})) res.push(v);
return res;
}, []);
DEMO: http://jsfiddle.net/nWjcp/4/
How to get the difference between two arrays in JavaScript?
This answer was written in 2009, so it is a bit outdated, also it's rather educational for understanding the problem. Best solution I'd use today would be
let difference = arr1.filter(x => !arr2.includes(x));
(credits to other author here)
I assume you are comparing a normal array. If not, you need to change the for loop to a for .. in loop.
function arr_diff (a1, a2) {
var a = [], diff = [];
for (var i = 0; i < a1.length; i++) {
a[a1[i]] = true;
}
for (var i = 0; i < a2.length; i++) {
if (a[a2[i]]) {
delete a[a2[i]];
} else {
a[a2[i]] = true;
}
}
for (var k in a) {
diff.push(k);
}
return diff;
}
console.log(arr_diff(['a', 'b'], ['a', 'b', 'c', 'd']));
console.log(arr_diff("abcd", "abcde"));
console.log(arr_diff("zxc", "zxc"));
How can I find matching values in two arrays?
Naturally, my approach was to loop through the first array once and check the index of each value in the second array. If the index is > -1
, then push
it onto the returned array.
Array.prototype.diff = function(arr2) {
var ret = [];
for(var i in this) {
if(arr2.indexOf(this[i]) > -1){
ret.push(this[i]);
}
}
return ret;
};
My solution doesn't use two loops like others do so it may run a bit faster. If you want to avoid using for..in
, you can sort both arrays first to reindex all their values:
Array.prototype.diff = function(arr2) {
var ret = [];
this.sort();
arr2.sort();
for(var i = 0; i < this.length; i += 1) {
if(arr2.indexOf(this[i]) > -1){
ret.push(this[i]);
}
}
return ret;
};
Usage would look like:
var array1 = ["cat", "sum","fun", "run", "hut"];
var array2 = ["bat", "cat","dog","sun", "hut", "gut"];
console.log(array1.diff(array2));
If you have an issue/problem with extending the Array prototype, you could easily change this to a function.
var diff = function(arr, arr2) {
And you'd change anywhere where the func originally said this
to arr2
.
Finding Common Values While Looping Over Two Arrays
You can reduce
the 1st array and use a forEach
loop over the second array to see if each of the values are equal, then push the value to the accumulator:
const arr1 = [{ kind: 'E', path: [ 'short_name' ], lhs: 'testing', rhs: 'testing1' }, { kind: 'E', path: [ 'agent_name' ], lhs: 'testing', rhs: 'testing2' }]const arr2 = [{ lhs: 'legacyId', rhs: 'id_number' }, { lhs: 'name.short', rhs: 'short_name' }, { lhs: 'name.long', rhs: 'agent_name' }, { lhs: 'gender', rhs: 'gender' }, { lhs: 'dob', rhs: 'date_of_birth' }]
const common = arr1.reduce((a, o1) => { const match = arr2.find(o2 => o1.path[0] === o2.rhs) match && a.push(match.rhs) return a}, [])
console.log(common)
Comparing two arrays of objects, and exclude the elements who match values into new array in JS
Just using the Array iteration methods built into JS is fine for this:
var result1 = [ {id:1, name:'Sandra', type:'user', username:'sandra'}, {id:2, name:'John', type:'admin', username:'johnny2'}, {id:3, name:'Peter', type:'user', username:'pete'}, {id:4, name:'Bobby', type:'user', username:'be_bob'}];
var result2 = [ {id:2, name:'John', email:'johnny@example.com'}, {id:4, name:'Bobby', email:'bobby@example.com'}];
var props = ['id', 'name'];
var result = result1.filter(function(o1){ // filter out (!) items in result2 return !result2.some(function(o2){ return o1.id === o2.id; // assumes unique id });}).map(function(o){ // use reduce to make objects with only the required properties // and map to apply this to the filtered array as a whole return props.reduce(function(newo, name){ newo[name] = o[name]; return newo; }, {});});
document.body.innerHTML = '<pre>' + JSON.stringify(result, null, 4) + '</pre>';
Java - Getting common element from two ArrayLists of different data type
for (User u : users) {
if (names.contains(u.getName()) {
System.out.println("Name: " + u.getName() + ", address: " + u.getAddress());
}
}
Get the unique values from two arrays and put them in another array
var array3 = array1.filter(function(obj) { return array2.indexOf(obj) == -1; });
MDN on Array#filter: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/filter
Includes a polyfill for older browsers.
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