[英]Excluding one item from list (by Index), and take all others
There is a List<int>
containing some set of numbers. 有一个
List<int>
包含一些数字。 Randomly I select an index, which will be processed separately (call it master ). 随机选择一个索引,将单独处理(称之为主索引)。 Now, I want to exclude this particular index, and get all other elements of
List
(call them slave ). 现在,我想要排除这个特定的索引,并获取
List
所有其他元素(称为slave )。
var items = new List<int> { 55, 66, 77, 88, 99 };
int MasterIndex = new Random().Next(0, items .Count);
var master = items.Skip(MasterIndex).First();
// How to get the other items into another List<int> now?
/* -- items.Join;
-- items.Select;
-- items.Except */
Join
, Select
, Except
- any of them, and how? Join
, Select
, Except
- 其中任何一个,以及如何?
EDIT: Cannot remove any item from the original list, otherwise I have to keep two lists. 编辑:无法删除原始列表中的任何项目,否则我必须保留两个列表。
You could remove Master item from the list, 您可以从列表中删除主项目,
List<int> newList = items.RemoveAt(MasterIndex);
RemoveAt() removes the item from the original list, So it's not necessary to assign the collection to a new list. RemoveAt()从原始列表中删除项目,因此没有必要将集合分配给新列表。 After calling RemoveAt(),
items.Contains(MasterItem)
would return false
. 调用RemoveAt()后,
items.Contains(MasterItem)
将返回false
。
If performance is an issue you may prefer to use the List.CopyTo method like this. 如果性能是一个问题,您可能更喜欢使用像这样的List.CopyTo方法。
List<T> RemoveOneItem1<T>(List<T> list, int index)
{
var listCount = list.Count;
// Create an array to store the data.
var result = new T[listCount - 1];
// Copy element before the index.
list.CopyTo(0, result, 0, index);
// Copy element after the index.
list.CopyTo(index + 1, result, index, listCount - 1 - index);
return new List<T>(result);
}
This implementation is almost 3 times faster than @RahulSingh answer. 这个实现几乎是@RahulSingh答案的3倍。
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