How to remove values from a list?

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Hello,
I have a List<featurelayer> in which all the layers are, and I also have a List<string> where I have the names of the layers that I want to keep in the previous list. How can I remove it? I tried it through the index but without success. List<string> seznamJmen is a list of the real names of the layers in List<featurelayer> vsechnyVrstvy.

What I have tried:

C#

 var seznamJmen = new List<string>();
List<FeatureLayer> vsechnyVrstvy = MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>().ToList();
 foreach (var jmena in seznamJmen)
                {
                    var index = vsechnyVrstvy.FindIndex(x => x.Name(jmena));
                }

Thanks for the advice and tips.

David

Posted 4-Oct-22 20:07pm

dejf111

Updated 4-Oct-22 21:29pm

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2 solutions

Solution 2

I think you can achieve what you need with one line of Linq. Something like this.

C#

List<(string name, int id)> names = new() { ("A", 0), ("B", 1),
                                                 ("C", 2), ("D", 3), ("E", 4) };
List<string> ids = new() { "B", "D", "A" };
var filteredList = names.Where(n=>ids.Contains(n.name)).ToList();

Posted 4-Oct-22 21:29pm

George Swan

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OriginalGriff · Accepted Answer · 2022-10-04T20:20:00

Solution 1

You can't remove anything from a collection if you are iterating through that collection in a foreach - that will automatically throw an exception.

Instead, in the foreach build a new "deletables" collection, and remove them once the foreach is finished - either with a second foreach, or using the Linq Except method:

C#

myList = myList.Except(deletables).ToList();

Posted 4-Oct-22 20:20pm

OriginalGriff

Comments

dejf111 5-Oct-22 3:08am

Thank you so much!

OriginalGriff 5-Oct-22 3:42am

You're welcome!

How to remove values ​​from a list?