C# sort Dictionary
last modified July 5, 2023
C# sort Dictionary tutorial shows how to sort Dictionary elements in C# language.
Sorting
In programming, sorting means arranging elements in an ordered sequence. Over the years, several algorithms were developed to perform sorting on data, including merge sort, quick sort, selection sort, or bubble sort.
The opposite of sorting, rearranging a sequence of elements in a random or meaningless order, is called shuffling. We can sort data alphabetically or numerically. The sort key specifies the criteria used to perform the sort.
C# has built-in methods for efficient sorting of data.
C# Sort Dictionary by value
The following example, we sort a small dictionary.
var users = new Dictionary<string, int>()
{
{ "John", 41 },
{ "Jane", 38 },
{ "Lucy", 29 },
{ "Paul", 24 }
};
var sorted = users.OrderBy(user => user.Value);
foreach (var user in sorted)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
Console.WriteLine("----------------------------");
var sorted2 = users.OrderByDescending(user => user.Value);
foreach (var user in sorted2)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
With OrderBy and OrderByDescending methods, we sort
the dictionary by its values in ascending and descending order.
$ dotnet run Paul is 24 years old Lucy is 29 years old Jane is 38 years old John is 41 years old ---------------------------- John is 41 years old Jane is 38 years old Lucy is 29 years old Paul is 24 years old
In the next example, we use the query expression syntax.
var users = new Dictionary<string, int>()
{
{ "John", 41 },
{ "Jane", 38 },
{ "Lucy", 29 },
{ "Paul", 24 }
};
var sorted = from pair in users
orderby pair.Value
select pair;
foreach (var user in sorted)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
Console.WriteLine("------------------------");
var sorted2 = from pair in users
orderby pair.Value descending
select pair;
foreach (var user in sorted2)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
The example sorts elements of a dictionary by its values in ascending and descending order using LINQ query expression syntax.
C# Sort Dictionary by keys
Next, we sort a dictionary by keys.
var users = new Dictionary<string, int>()
{
{ "John", 41 },
{ "Jane", 38 },
{ "Lucy", 29 },
{ "Paul", 24 }
};
var sorted = users.OrderBy(user => user.Key);
foreach (var user in sorted)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
Console.WriteLine("----------------------------");
var sorted2 = users.OrderByDescending(user => user.Key);
foreach (var user in sorted2)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
The example sorts dictionary elements by its keys in ascending and descending
order using OrderBy and OrderByDescending methods.
$ dotnet run Jane is 38 years old John is 41 years old Lucy is 29 years old Paul is 24 years old ---------------------------- Paul is 24 years old Lucy is 29 years old John is 41 years old Jane is 38 years old
C# SortedDictionary
SortedDictionary represents a collection of key/value pairs
that are sorted on the key.
var sortedUsers = new SortedDictionary<string, int>()
{
{ "John", 41 },
{ "Jane", 38 },
{ "Lucy", 29 },
{ "Paul", 24 }
};
foreach (var user in sortedUsers)
{
Console.WriteLine($"{user.Key} is {user.Value} years old");
}
The example demonstrates the usage of the SortedDictionary.
Source
SortedDictionary class - language reference
In this article we sorted Dictionary elements in C# language.
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