Python OrderedDict

Python OrderedDict is a subclass of the built-in dict class. It maintains the order of the elements in which they were added. In a regular dictionary, the order of the elements is arbitrary. However, in OrderedDict, the order of the elements is preserved.

Syntax

class collections.OrderedDict([items])

Parameters

• items (optional) - A sequence of (key, value) pairs or keyword arguments as arguments. This can be used to initialize the OrderedDict.

Example

from collections import OrderedDict

# creating an ordered dictionary
my_dict = OrderedDict()

# adding elements to the dictionary
my_dict['a'] = 1
my_dict['b'] = 2
my_dict['c'] = 3

# printing the dictionary
print(my_dict)

The output of the above code will be:

OrderedDict([('a', 1), ('b', 2), ('c', 3)])

Conclusion

Python OrderedDict is used when you want to preserve the order of elements in a dictionary. It is very useful in scenarios where the order of elements is important, like in parsing XML files or processing HTTP headers.