How to remove duplicate elements from an array in Swift 5? [duplicate] - swift

This question already has answers here:
Removing duplicate elements from an array in Swift
(49 answers)
How to merge two custom type arrays and remove duplicate custom type items in Swift?
(2 answers)
Remove objects with duplicate properties from Swift array
(16 answers)
Closed 3 years ago.
I have an array of custom objects, a.k.a users, and some of them are duplicates.
How can I make sure there is only one of each element? No duplicates.
Also, what's the most efficient way?
var users: UserModel = [UserModel]()

Most efficient way if you don’t care about maintaining the original order in the array
let uniqueUsers = Array(Set(users))

Maybe instead of using an array you want to use a set? https://developer.apple.com/documentation/swift/set

Related

PostgreSQL IN matches any value in list - how do I match all values in list? [duplicate]

This question already has answers here:
PostgreSQL where all in array
(9 answers)
Closed 2 years ago.
In PostgreSQL IN can be used to match any value in a list. What if I need to match all values in a list? Is there a way to do this in PostgreSQL?
try = ALL (subquery) instead of IN (see manual)

How Can I update Custom index an array [duplicate]

This question already has answers here:
Flutter: Update specific index in list (Firestore)
(2 answers)
Closed 2 years ago.
I need some help in flutter and firestore. I have an object inside an array in my collocation Is there any way to update object custom an array?
You can access and update anything inside an array by accessing it like you would any other array:
final List<SomeObject> _someObjects = <SomeObject>[];
...
for SomeObject s in _someObjects)
doSomethingWith(s);

How to find the array indexes for each element in another array in MATLAB? [duplicate]

This question already has answers here:
How to find the index array of a array of elements?
(3 answers)
Closed 8 years ago.
There are two arrays:
A=[2,6,9,10];
B=[6,10,9,2,2,9,10,10,6,6,2,9];
I want to output the following array:
C=[2,4,3,1,1,3,4,4,2,2,1,3];
How to do this work?
I found the solution, [~,C]=ismember(B,A);
My answer shall be C=arrayfun(#(x) find(A==x),B)

How do I make a mongodb find where a field(object) includes all properties from my query (names and values)? [duplicate]

This question already has answers here:
MongoDB - how to query for a nested item inside a collection?
(3 answers)
Closed 9 years ago.
Consider my query to be: {cheese:"Cheddar"} and I have the following collections:
{vegetable:"Lettuce", cheese:"Cheddar"}, {cheese:"Blue"}, {milk:"Chocolate}, {cheese:"Cheddar"}
How do I make a find that returns me all collections that include cheese:Cheddar?
The result would be {vegetable:"Lettuce", cheese:"Cheddar"}, {cheese:"Cheddar"} but right now it fives me just {cheese:"Cheddar"}. From what I investigated I only found tokens to work with arrays.
I do NOT know the name of the property is cheese, nor do I know if there are any other ingredients.
I am looking for a way to get documents from a collection, where the query is included in a field, by the names of the properties in the query and the respective values.
Using db.collection.findOne({cheese:"Cheddar"}) you will get as a result only one document, maybe {cheese:"Cheddar"} or maybe {vegetable:"Lettuce", cheese:"Cheddar"}, the first one that MongoDB finds depending on the _id field. If what you want is getting both, you should use db.collection.find({cheese:"Cheddar"}).

mongodb $in limit [duplicate]

This question already has answers here:
What is the maximum number of parameters passed to $in query in MongoDB?
(4 answers)
Closed 6 years ago.
Was just wondering if there is a limit to Mongodb's $in function?
http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24in
I have a collection of users (BIG) and have a smaller subset of ObjectIds stashed somewhere, and I want to select all users (collections) that are in my ObjectIds.
Thanks
Since there's no limit on the number of items in an array as such, you shouldn't have any problem..
For the case when the array is embedded inside a document, you might want to have a look at these:
http://groups.google.com/group/mongodb-user/browse_thread/thread/4a7caeba972aa998?fwc=1
Filtering content based on words
http://groups.google.com/group/mongodb-user/browse_thread/thread/28ae76e5ad5fcfb5