Some useful LINQ extensions like IComparer(T) and IEqualityComparer(T) lambda wrappers, linq permutations, linq merge, linq flatten.
You can use IEnumerable.Shuffle() to shuffle arrays etc. For example:
var numbers = Enumerable.Range(0, 15);
string output = "";
numbers.Shuffle().ToList().ForEach(item =>
{
output += item.ToString() + " ";
});
Console.WriteLine(output);
Will result in something like:
14 3 5 6 4 13 2 7 8 9 10 11 0 1 12
You can use IEnumerable.OrderBy and OrderByDescending with two lambda expressions instead of creating new instance of IComparer, for example:
numbers.OrderBy(i=>i,(i1,i2)=>i1-i2)First argument is keySelector, second is the comparer function.
You can use IEnumerable.Distinct with one or two lambda expressions. First expression is a equality comparer function, second is GetHashCode function. If you skip second expression, the default (i=>1) will be used, and therefore you can use only comparer function like in the example bellow.
var something = new string[]
{
"John",
"JoHn",
"Jack",
"JACK",
"Lisbeth",
"Vincent",
"VINcent"
};
string output = "";
something.Distinct((a,b)=>a.ToLower()==b.ToLower()).ToList().ForEach(item =>
{
output += item.ToString() + " ";
});
Console.WriteLine(output);Above will output:
John Jack Lisbeth Vincent
You can use IEnumerable.Permutations to lazy-generate permutations of your arrays etc. For example:
foreach (var permutation in Enumerable.Range(1,4).Permutations())
{
string output = "";
permutation.ToList().ForEach(item =>
{
output += item.ToString() + " ";
});
Console.WriteLine(output);
}Will result in:
1 2 3 4
1 2 4 3
1 3 2 4
1 3 4 2
1 4 2 3
1 4 3 2
2 1 3 4
2 1 4 3
2 3 1 4
2 3 4 1
2 4 1 3
2 4 3 1
3 1 2 4
3 1 4 2
3 2 1 4
3 2 4 1
3 4 1 2
3 4 2 1
4 1 2 3
4 1 3 2
4 2 1 3
4 2 3 1
4 3 1 2
4 3 2 1
You can also provide IEqualityComparer lambda and get permutations of any objects (this is a non-creative example):
var array = new dynamic[3];
for (int i = 0; i < 3; i++)
{
dynamic something = new { letter = (char)(65 + i) };
array[i] = something;
}
foreach (var permutation in array.Permutations((o, o1) => o.letter == o1.letter))
{
string output = "";
permutation.ToList().ForEach(item =>
{
output += item.letter.ToString() + " ";
});
Console.WriteLine(output);
}And the result will be:
A B C
A C B
B A C
B C A
C A B
C B A
You can use IEnumerable.Flatten, to flatten deeply nested collections. There are two implementations - recursive and non recursive. Example:
var array = new dynamic[]
{
new[] {"lol", "xyz", "abc"},
new dynamic[] {"lol2", new dynamic[] {"nested1", new[] {"nested2","nested2-other"}}},
"trolo"
};
var result = array.Flatten<string>();
//or non recursive implementation:
result = array.Flatten<string>(false);
Result:
[0]: "lol"
[1]: "xyz"
[2]: "abc"
[3]: "lol2"
[4]: "nested1"
[5]: "nested2"
[6]: "nested2-other"
[7]: "trolo"
You can use
LinqCollections.Merge<T>(Func<T,T,int> compare,params IList<T>[] toMerge)
to merge any number of lists (they should be sorted). There is an additional overload which can remove duplicates:
LinqCollections.Merge<T>(Func<T,T,int> compare,true,params IList<T>[] toMerge)
Example 1:
var array1 = Enumerable.Range(0, 15).Where(i=>i%3==0).ToList();
var array2 = Enumerable.Range(0, 15).Where(i=>i%3==1).ToList();
var array3 = Enumerable.Range(0, 15).Where(i=>i%3==2).ToList();
var result = LinqCollections.Merge((a, b) => a - b, array1, array2,array3);
Result 1:
[0]: 0
[1]: 0
[2]: 0
[3]: 0
[4]: 0
[5]: 1
[6]: 1
[7]: 1
[8]: 1
[9]: 1
[10]: 2
[11]: 2
[12]: 2
[13]: 2
[14]: 2
Example 2 (remove duplicates):
var array1 = Enumerable.Range(0, 1000).Select(i => 2).ToList();
var array2 = Enumerable.Range(0, 1000).Select(i => 1).ToList();
var result = LinqCollections.Merge((a, b) => a - b,true, array1, array2);
Result 2:
[0]: 1
[1]: 2
You can use IEnumerable.MinWithIndex to get Tuple of your Type & Index of minimum element from Enumerable.