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What are pickling and unpickling in Python?

Vinisha Maheshwari

In this shot, we will discuss pickling and unpickling in Python.

Pickle is a module in Python that is primarily used to serialize and de-serialize a Python object structure. Both pickling and unpickling become essential when we have to transfer Python objects from one system to another.

  • Pickling is a process by which the object structure in Python is serialized. A Python object is converted into a byte stream when it undergoes pickling.

  • Unpickling is a process by which original Python objects are retrieved from the stored string representation i.e., from the pickle file. It converts the byte stream into a Python object.


To understand this better let’s look at the code snippet below.

import pickle
my_list = {15, 'Python', 'Hello World'}
# Pickling
with open("data.pickle","wb") as file_handle:
    pickle.dump(my_list, file_handle, pickle.HIGHEST_PROTOCOL)
# Unpickling
with open("data.pickle","rb") as file_handle:
    retrieved_data = pickle.load(file_handle)


  • In line 1, we import the pickle module in Python.

  • In line 2, a demo Python list is created which will be pickled.

  • In lines 4 and 5, pickling is done. A .pickle file is created and the Python object (here demo Python list) is dumped.

  • In lines 7 to 9, we have unpickled the pickled file which thereby gives the demo Python list that was created as an output.

Note :

  • The dump() function is used to serialize an object hierarchy.
  • pickle.HIGHEST_PROTOCOL is an integer value that represents the highest available protocol version.
  • The load() function is used to de-serialize a data stream.

In this way, we can use pickling and unpickling in Python. It is a tool of immense importance when we want to preserve our work for later use, especially due to the fact that it can serialize almost any Python object without any boilerplate.



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