C#•2y ago

✅ Comparing properties of a values of lists

i have 2 lists List<Animal> and List<Dog> and both Animal and Dog have the property id i'm trying to insert a list of Dog into the list of Animal but i don't want to insert Animals with duplicate id's

51 Replies

NinjaOla•2y ago

paste this question into chatgpt. and i think u will be happy with your answer also bonus: ask it to explain

Pobiega•2y ago

List<Dog> dogs = new List<Dog>();
List<Animal> animals = new List<Animal>();

List<Dog> dogsNotInAnimals = ...;

animals.AddRange(dogsNotInAnimals);

List<Dog> dogs = new List<Dog>();
List<Animal> animals = new List<Animal>();

List<Dog> dogsNotInAnimals = ...;

animals.AddRange(dogsNotInAnimals);

can you think of a way to calculate dogsNotInAnimals?

LividOP•2y ago

i mean might there be a performance issue if List<Animal> is quite big

Pobiega•2y ago

sure, but then you shouldn't be having a list in the first place

LividOP•2y ago

but then i won't be improving my explanation skills😔

Thinker•2y ago

don't do that lmao

NinjaOla•2y ago

Now i wonder eiter my skills are bad or i got something else from it than you?

Thinker•2y ago

wat

LividOP•2y ago

wat

Pobiega•2y ago

wat

NinjaOla•2y ago

Ask chatgpt for an explaination and solution

Thinker•2y ago

If you're gonna tell someone to just go ask a text prediction engine then why even respond in the first place? This person asked a question, you gave them a non-answer If they wanted to use chatgpt then they would've done that

NinjaOla•2y ago

Ah then i understand

Thinker•2y ago

they asked a question here

NinjaOla•2y ago

I think its a tool that is often not looked at, so

Thinker•2y ago

it's looked at too much lmao

LividOP•2y ago

i know how to do it however

Pobiega•2y ago

Don't.

LividOP•2y ago

i was asking if there is a better way than looping

Pobiega•2y ago

Plenty

LividOP•2y ago

gimme

Pobiega•2y ago

Assuming we can change some types around if you are working with two lists, there isnt much we can do Can you think of a collection type that could be used to help with the "unique id" requirement?

LividOP•2y ago

wat

Pobiega•2y ago

what part of that question made you go wat?

LividOP•2y ago

wat

Pobiega•2y ago

so I know what to explain

LividOP•2y ago

collection type?

Pobiega•2y ago

List<T> is a collection type T[] (array) is also a collection type can you name some more?

LividOP•2y ago

why T?

Pobiega•2y ago

its just a placeholder for the actual type

LividOP•2y ago

Pobiega•2y ago

by convention we use the letter T for that

LividOP•2y ago

hashmap

Pobiega•2y ago

Yep!

LividOP•2y ago

dictionary

Pobiega•2y ago

yep! called HashSet in C#, but its the same

LividOP•2y ago

oh yes

Pobiega•2y ago

so what do hashsets and dictionaries have as their "special" property?

LividOP•2y ago

no duplicate?

Pobiega•2y ago

thats hashsets, yes dictionaries are keyed meaning you set a key for each value, and you can only have one item per key do one of these sound good for storing a list of items with unique IDs?

LividOP•2y ago

so you can set id as the key for dictionaries?

Pobiega•2y ago

that sounds like an excellent idea

LividOP•2y ago

but i still have to loop to convert from list to dictionary

Pobiega•2y ago

for one, it makes it O(1) to look if an ID already exists

LividOP•2y ago

oh wait i don't know if i can

Pobiega•2y ago

instead of O(N)

LividOP•2y ago

since i'm using a winform datasource

Pobiega•2y ago

okay You're a beginner, right?

LividOP•2y ago

sorta yes

Pobiega•2y ago

Don't think you need to worry about performance of filtered list inserts etc just yet 🙂

LividOP•2y ago

i tried using a directory / bindingsource

        BindingSource bs = new BindingSource()
        {
            DataSource = _artikelsDic.Values.ToList(),
            
        };

        BindingSource bs = new BindingSource()
        {
            DataSource = _artikelsDic.Values.ToList(),
            
        };

but it doesn't update correctly how should i do it?

BindingSource bs = new BindingSource()
        {
            DataSource = _artikelsList,
            DataMember = "value"
            
        };

BindingSource bs = new BindingSource()
        {
            DataSource = _artikelsList,
            DataMember = "value"
            
        };

this gives me only one value? dead chat

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✅ Comparing properties of a values of lists

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