Few mistakes when using Python dictionary

Usually, A dictionary is a collection which is unordered, changeable and indexed. In Python, dictionaries are written with curly brackets, and they have keys and values. Each key-value pair in a Dictionary is separated by a ‘colon’, whereas each key is separated by a ‘comma’.

my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
print(my_dict)

Output:

{1: 'Geeks', 2: 'For', 3: 'Geeks'}

We generally use dictionaries to access the items with its key value, inside square brackets.

my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
print(my_dict[1])
print(my_dict[2])
print(my_dict[3])

Output:

Geeks
For
Geeks

The common operations of dictionaries are:

• To get the values of the dictionary we use values() method.

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  print(my_dict.values())
  Output:
  
  

  dict_values(['Geeks', 'For', 'Geeks'])
  

• To get the keys of the dictionary we use keys() method.

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  print(my_dict.keys())
  Output:

  dict_keys([1, 2, 3])
  

• To add a new entry into the dictionary

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  my_dict[4]='Python'
  print(my_dict)
  Output:

  {1: 'Geeks', 2: 'For', 3: 'Geeks', 4: 'Python'}
  

• To change the value of the entry

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  my_dict[3]='Python'
  print(my_dict)
  Output:

  {1: 'Geeks', 2: 'For', 3: 'Python'}
  

• To delete an entry from dictionary

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  del my_dict[3]
  print(my_dict)
  Output:

  {1: 'Geeks', 2: 'For'}
  

• To copy the dictionary

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  my_dict1 = my_dict
  print(my_dict1)
  Output:

  {1: 'Geeks', 2: 'For', 3: 'Geeks'}
  

• To remove all entries.

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  my_dict.clear()
  print(my_dict)
  Output:

  {}
  

• To find the number of entries.

  my_dict = {1: 'Geeks', 2: 'For', 3:'Geeks'}
  z = len(my_dict)
  print(z)
  Output:

  3
  

Common mistakes while using dicts and overcomes

• To access the value of the key, we generally use dict_name[key_name] instead we should use get() method to get rid of the exceptions thrown all throughout your code.
• To update the value of the key, we generally use dict_name[key_name]=’new_value’ instead we should update(key=value) method to get rid of the exceptions thrown all throughout your code.
• To copy the dictionary, we generally use dict_name = new_dict_name instead we should use copy() method to get rid of the exceptions thrown all throughout your code.

When not to use dicts

• Dicts are useful but they’re not the only associative array structure in Python. Often there is a more specialised container type like set, tuple etc.
• Numeric values with different types can be equal (e.g. 1 == 1.0), in which case they represent the same key.