How to convert list to Dictionary in c#?

How to convert list to Dictionary in c#?

Conversion Between Array List and Dictionary in C#

  1. Convert an array to a List – Use ToList() method.
  2. Convert a list to an array – Use ToArray() method.
  3. Convert a List to a Dictionary – Use ToDictionary() method.
  4. Convert an array to a Dictionary – Use ToDictionary() method.

How to get enum in list?

The idea is to use the Enum. GetValues() method to get an array of the enum constants’ values. To get an IEnumerable of all the values in the enum, call Cast() on the array. To get a list, call ToList() after casting.

When to use Dictionary and when to use list in c#?

The Find() method of the List class loops thru each object in the list until a match is found. So, if we want to look up a value using a key, then a dictionary is better for performance over the list. So, we need to use a dictionary when we know the collection will be primarily used for lookups.

Is a Dictionary faster than a list c#?

Of course the Dictionary in principle has a faster lookup with O(1) while the lookup performance of a List is an O(n) operation. The Dictionary map a key to a value and cannot have duplicate keys, whereas a list just contains a collection of values. Also Lists allow duplicate items and support linear traversal.

How do you turn a dictionary into a list?

To perform this particular task there are many ways of converting a dictionary to a list.

  1. By using .items() method.
  2. By using .values() method.
  3. By using zip() function.
  4. By using .keys() method.
  5. By using list comprehension method.
  6. By using map function.

Can we convert list to dictionary in Python?

You can convert a Python list to a dictionary using the dict. fromkeys() method, a dictionary comprehension, or the zip() method. The zip() method is useful if you want to merge two lists into a dictionary.

Can we return enum in C#?

Enum Class Methods Returns true one or more bit fields are set in the current instance. Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumerated object. Returns the string representation of the value of this instance.

Why use a dictionary instead of a list?

It is more efficient to use dictionaries for the lookup of elements as it is faster than a list and takes less time to traverse. Moreover, lists keep the order of the elements while dictionary does not.

Are dictionaries or lists faster for lookups?

Lookups are faster in dictionaries because Python implements them using hash tables. If we explain the difference by Big O concepts, dictionaries have constant time complexity, O(1) while lists have linear time complexity, O(n).

Is dictionary more efficient than list?

A dictionary is 6.6 times faster than a list when we lookup in 100 items.

How do you flatten a list of lists?

Turning a list of lists into a list is called “flattening a list.”…There are three ways to flatten a Python list:

  1. Using a list comprehension.
  2. Using a nested for loop.
  3. Using the itertools. chain() method.

How we can create a list of tuples from the values of a dictionary of lists?

Use dict. items() to convert a dictionary into a list of tuples

  1. a_dictionary = {“a”: 1, “b”: 2, “c”: 3}
  2. a_view = a_dictionary. items()
  3. a_list = list(a_view)
  4. print(a_list)

How do I convert a list to a dictionary?

To convert a list to a dictionary using the same values, you can use the dict. fromkeys() method. To convert two lists into one dictionary, you can use the Python zip() function. The dictionary comprehension lets you create a new dictionary based on the values of a list.

How do I extract a dictionary from a list?

How to Extract Dictionary Values as a List

  1. (1) Using a list() function: my_list = list(my_dict.values())
  2. (2) Using a List Comprehension: my_list = [i for i in my_dict.values()]
  3. (3) Using For Loop: my_list = [] for i in my_dict.values(): my_list.append(i)

Is enum or constant better?

Enums limit you to the required set of inputs whereas even if you use constant strings you still can use other String not part of your logic. This helps you to not make a mistake, to enter something out of the domain, while entering data and also improves the program readability.

Can list be used as keys of a dictionary?

Second, a dictionary key must be of a type that is immutable. For example, you can use an integer, float, string, or Boolean as a dictionary key. However, neither a list nor another dictionary can serve as a dictionary key, because lists and dictionaries are mutable.

How to cast a list to a dictionary using LINQ?

What is the best way with LINQ to cast my list to: Show activity on this post. It sounds like you want to group the MyObject instances by KeyedProperty and put that grouping into a Dictionary >. If so then try the following Show activity on this post. List list = …;

How to convert list to dictionary in Python?

ToDictionary method converts List to Dictionary while giving you the hand to choose the dictionary key (thanks to the lambda expression). You need to be careful from raising an exception when you insert an already existing key such as this example:

How do I retrieve a list from a mydictionary?

MyDictionary.Add (createListName, new List ()); Console.WriteLine (“Input a string to retrieve a list:”); var retrieveListName = Console.ReadLine (); // As long as they input the same string… List retrievedList = MyDictionary [retrieveListName];

How to get the number of lists in a text file?

Edit: If you want a certain number of lists, use a dictionarym apping from int to string, not string to string: int maxNumberOfLists = 5; // or whatever you read from your text file.