C#•8mo 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•8mo ago

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

Pobiega•8mo 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?

Livid•8mo ago

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

Pobiega•8mo ago

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

Livid•8mo ago

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

Thinker•8mo ago

don't do that lmao

NinjaOla•8mo ago

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

Thinker•8mo ago

wat

Livid•8mo ago

wat

Pobiega•8mo ago

wat

NinjaOla•8mo ago

Ask chatgpt for an explaination and solution

Thinker•8mo 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•8mo ago

Ah then i understand

Thinker•8mo ago

they asked a question here

NinjaOla•8mo ago

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

Thinker•8mo ago

it's looked at too much lmao

Livid•8mo ago

i know how to do it however

Pobiega•8mo ago

Don't.

Livid•8mo ago

i was asking if there is a better way than looping

Pobiega•8mo ago

Plenty

Livid•8mo ago

gimme

Pobiega•8mo 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?

Livid•8mo ago

wat

Pobiega•8mo ago

what part of that question made you go wat?

Livid•8mo ago

wat

Pobiega•8mo ago

so I know what to explain

Livid•8mo ago

collection type?

Pobiega•8mo ago

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

Livid•8mo ago

why T?

Pobiega•8mo ago

its just a placeholder for the actual type

Livid•8mo ago

Pobiega•8mo ago

by convention we use the letter T for that

Livid•8mo ago

hashmap

Pobiega•8mo ago

Yep!

Livid•8mo ago

dictionary

Pobiega•8mo ago

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

Livid•8mo ago

oh yes

Pobiega•8mo ago

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

Livid•8mo ago

no duplicate?

Pobiega•8mo 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?

Livid•8mo ago

so you can set id as the key for dictionaries?

Pobiega•8mo ago

that sounds like an excellent idea

Livid•8mo ago

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

Pobiega•8mo ago

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

Livid•8mo ago

oh wait i don't know if i can

Pobiega•8mo ago

instead of O(N)

Livid•8mo ago

since i'm using a winform datasource

Pobiega•8mo ago

okay You're a beginner, right?

Livid•8mo ago

sorta yes

Pobiega•8mo ago

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

Livid•8mo 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