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I have two lists
List<T> list1 = new List<T>();
List<T> list2 = new List<T>();
I want remove all elements from list1, which also exist in list2. Of course I can loop through the first loop looking for each element in list2, but I am looking for elegant solution.
Thanks!
846
How to Remove an Element from a List Using the remove() Method in Python. To remove an element from a list using the remove() method, specify the value of that element and pass it as an argument to the method. remove() will search the list to find it and remove it.
RemoveAt (Int32) Method is used to remove the element at the specified index of the List<T>. Properties of List: It is different from the arrays.
The best way to remove items from a list while iterating over it is to use RemoveAll() .
In Python, use list methods clear() , pop() , and remove() to remove items (elements) from a list. It is also possible to delete items using del statement by specifying a position or range with an index or slice.
To change the actual list1 in place, you could use
list1.RemoveAll(item => list2.Contains(item));
You might instead prefer to simply have a query over the lists without modifying either
var result = list1.Except(list2);
LukeH makes a good recommendation in the comments. In the first version, and if list2 is particularly large, it might be worth it to load the list into a HashSet<T> prior to the RemoveAll invocation. If the list is small, don't worry about it. If you are unsure, test both ways and then you will know.
var theSet = new HashSet<YourType>(list2);
list1.RemoveAll(item => theSet.Contains(item));
With LINQ:
var result = list1.Except(list2);
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