Hi There, In this post we’ll learn about python dictonary comprehensions and it’s usage.

Dictonary comprehensions

Dictonary comprehensions are used for creating new Dictonary from another iterables.

Dictonary comprehensions for loop:

• multiplying dict values with 2 using For loop

    >>> my_dict = {'A': 1, 'B': 2, 'C': 3, 'D': 4}
    >>> for key, vale in my_dict.items():
    ...     my_dict[key] = vale * 2
    ...
    >>> my_dict
    {'A': 2, 'C': 6, 'B': 4, 'D': 8}
    >>>
  

• Using Dictonary comprehensions the above program can be written as follows

    >>> my_dict = {'A': 1, 'B': 2, 'C': 3, 'D': 4}
    >>> my_dict = {key : value * 2 for key, value in my_dict.items()}
    >>> my_dict
    {'A': 2, 'C': 6, 'B': 4, 'D': 8}
    >>>
  

Dictonary comprehensions for loop and if condiation:

• Finding even numbers from given list and storing into dictonary

    >>> numbers = [1, 2, 3, 4, 5, 6, 7, 8]
    >>> result = {}
    >>> for num in numbers:
    ...     if num % 2 == 0:
    ...         result[num] = "Even"
    ...     else:
    ...         result[num] = "Odd"
    ...
    >>> result
    {1: 'Odd', 2: 'Even', 3: 'Odd', 4: 'Even', 5: 'Odd', 6: 'Even', 7: 'Odd', 8: 'Even'}
    >>>
  

• Using Dictonary comprehensions the above program can be written as follows

    >>> numbers = [1, 2, 3, 4, 5, 6, 7, 8]
    >>> result = {num: ("Even" if num % 2 == 0 else "Odd") for num in numbers}
    >>> result
    {1: 'Odd', 2: 'Even', 3: 'Odd', 4: 'Even', 5: 'Odd', 6: 'Even', 7: 'Odd', 8: 'Even'}
    >>>