How to get Alternate elements using Enumerable in C#
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29-09-2019 - |
Pergunta
This is a continuation of my question: How to get reverse of a series of elements using Enumarable in C#?
Now I need alternate elements only. Here is my solution using for
loop:
int Max = 10;
int limit = 5;
Dictionary<String , String> MyDict = new Dictionary<string,string>();
int j = 0;
for (int i = 0; i <Max; i++)
{
if (i >= limit)
MyDict.Add((i+1).ToString(), "None");
else
MyDict.Add((i+1).ToString(), j.ToString());
j+=2;
}
The output is like
{ "1" "0"}
{ "2" "2"}
{ "3" "4"}
{ "4" "6"}
{ "5" "8"}
{ "6" "None"}
{ "7" "None"}
{ "8" "None"}
{ "9" "None"}
{ "10" "None"}
How to do this using Enumarerable
or Using any LINQ method. And also the reverse like my previous question: How to get reverse of a series of elements using Enumarable in C#?
Solução
You could use the standard LINQ Where
extension method as a basis for doing what you need.
Given a list of IEnumerable<T>
it would work like this:
var evens = list.Where((t, i) => i % 2 == 0);
var odds = list.Where((t, i) => i % 2 == 1);
Hopefully you can build on these to do what you want.
Outras dicas
int max = 10;
int limit = 5;
var dict = Enumerable.Range(1, max)
.ToDictionary(x => x.ToString(),
x => (x > limit) ? "None"
: ((x - 1) * 2).ToString());
I don't think there is a standard LINQ method that does this. But you can create custom IEnumerable extension methods to do this sort of thing.
http://msdn.microsoft.com/en-us/library/cc981895.aspx
Alternate elements is one of the examples here. Basically it's just taking your example code and packaging it as an extension so you get the syntax you want.