Dictionaries Continued

• Assignments:

  • As with lists, if you make a change in dictionary, it will reflect to all the names that refer to it

• Shallow Copy

  • To copy keys and values from a dictionary to other dictionary we can use copy()
  • This method is shallow copy and works if the dictionary values are immutable.
  • If you dictionary contains the values which are mutable prefer deepcopy()

• Deep Copy

• Iterating dictionary with for and in Refer Here

• Dictionary Comprehensions:

  • The syntax of dictionary comprehensions is

  { key_expression: value_expression for expression in iterable }
  

  • Lets try to count the number of words in a letter and display them as dictionary

  word = 'letters'
  
  { 'l': 1, 'e': 2, 't': 2, 'r': 1, 's': 1 }
  

  • The program using normal for in will be

    word = input('Enter any word: ')
    letter_dict = {}
    for letter in word:
        if letter in letter_dict:
            letter_dict[letter] += 1
        else:
            letter_dict[letter] = 1
    print(letter_dict)
    

  • Refer Here for the dictionary comprehension
  • Refer Here for other dictionary methods

Rules of Dictionary

1. Keys must be unique
2. Keys must be immutable i.e. key can be int, float, string, tuple

Project Euler Problem 5

• Refer Here
• Refer Here for the solution