Convert an array to dictionary with value as index of the item and key as the item itself

by

You can use the overload of Select which includes the index:

var dictionary = array.Select((value, index) => new { value, index })
                      .ToDictionary(pair => pair.value, pair => pair.index);

Or use Enumerable.Range:

var dictionary = Enumerable.Range(0, array.Length).ToDictionary(x => array[x]);

Note that ToDictionary will throw an exception if you try to provide two equal keys. You should think carefully about the possibility of your array having two equal values in it, and what you want to happen in that situation.

I’d be tempted just to do it manually though:

var dictionary = new Dictionary<string, int>();
for (int i = 0; i < array.Length; i++)
{
    dictionary[array[i]] = i;
}

More Related Contents:

  1. How to read lines to dictionary with linQ [closed]
  2. Convert list to dictionary using linq and not worrying about duplicates
  3. Remove Item in Dictionary based on Value
  4. LINQ query to return a Dictionary
  5. Good way to get the key of the highest value of a Dictionary in C#
  6. How to sort a dictionary by key
  7. A dictionary where value is an anonymous type in C#
  8. Map two lists into a dictionary in C#
  9. Fluent and Query Expression — Is there any benefit(s) of one over other?
  10. linq case statement
  11. XDocument containing namespaces
  12. Use own IComparer with Linq OrderBy
  13. How to convert list of arrays into a multidimensional array
  14. Am I misunderstanding LINQ to SQL .AsEnumerable()?
  15. An expression tree lambda may not contain a null propagating operator
  16. VB.NET equivalent to C# var keyword [duplicate]
  17. Create Items from 3 collections using Linq
  18. Different ways of adding to Dictionary
  19. How do I do a left outer join with Dynamic Linq?
  20. Composite Key Dictionary
  21. Filtering out values from a C# Generic Dictionary
  22. Creating a LINQ select from multiple tables
  23. What benefits does dictionary initializers add over collection initializers?
  24. How to convert DataTable to class Object?
  25. Using LINQ to find item in a List but get “Value cannot be null. Parameter name: source”
  26. Get different and common items in two arrays with LINQ [closed]
  27. LINQ: differences between single Where with multiple conditions and consecutive Wheres with single condition [duplicate]
  28. Intersect with a custom IEqualityComparer using Linq
  29. using LINQ to find the cumulative sum of an array of numbers in C#
  30. Can I use a TryParse inside Linq Comparable?

Leave a Comment