6 useful extensions for IEnumerable

[giscus[bot]]

6 useful extensions for IEnumerable

I did already write about some useful extension methods for Task and ValueTask. Today I want to show you some useful extension methods for IEnumerable.

https://steven-giesel.com/blogPost/1b8eaaef-01a3-4799-9a96-f0d37197d175

[savemysoul382]

Hello, in your Swap method, the random type is not initialized anywhere, but is used

[linkdotnet]

The idea is that you pass in your collection you want to shuffle. The shuffle method itself doesn’t create anything more than just bringing the elements in a random order.

Maybe I am missing something. Can you explain a bit more in detail?

[jamescurran]

Swap uses an object named random which is never declared or initialized. (Personally, I like putting a Random object as a singleton in my IoC container, and having it injected into my services)

[jamescurran]

Sorry, not Swap(), -- Shuffle()

[linkdotnet]

Yes I missed that. Originally it was a field in a class. I updated the implementation so it uses Random.Shared.

Much appreciated!

[maikschott]

Partitioning into two or more collections can also be done using the in-builtToLookup LINQ method.

var evenOdd = numbers.ToLookup(n => n % 2 == 0);
var (even, odd) = (evenOdd[true], evenOdd[false]);

The Partition method could then likewise be shortened to:

public static (IEnumerable<T> True, IEnumerable<T> False) Partition<T>(
        this IEnumerable<T> source,
        Func<T, bool> predicate)
{
  var partitions = source.ToLookup(predicate);
  return (partitions[true], partitions[false]);
}

[linkdotnet]

Ohh I like that one. Did not come into my mind.

Yes more concise and readable!

[jamescurran]

I was going to say the you should change the return type of Partition to use IList<T>s instead of IEnumerable<T>s, as the implementation use List<>s so there's no point in limiting what we can do with the results.

But, if you use the ToLookup() implementation, we have to stay with IEnumerable<>