title: Pickling in Python
Pickling refers to the serialization and deserialization of an object in Python. It essentially stores an object to a file so the user can load it later on. During pickling, the Python object is converted to a binary stream.
First let’s create a class:
class ExampleClass(): def __init__(self, integer, string, number_list): self.integer = integer self.string = string self.number_list = number_list def print_attributes(self): print(self.integer, self.string, self.number_list) def print_sum(self): print(sum(self.number_list)) instance = ExampleClass(10, 'rubberducky', [1, 2, 3, 1, 2]) instance.print_attributes() # Prints 10 rubberducky [1, 2, 3, 1, 2] instance.print_sum() # Prints 9
Now, let’s try pickling it:
import pickle with open('file.pickle', 'wb') as file: pickle.dump(instance, file)
This creates the file
file.pickle. According to this StackOverflow thread, Python 3’s preferred extension is
.pickle. Now we simply need to lead it:
import pickle with open('file.pickle', 'rb') as file: loaded = pickle.load(file) loaded.print_attributes() # Prints 10 rubberducky [1, 2, 3, 1, 2] loaded.print_sum() # Prints 9
It works! Note that both times,
open()‘s mode was
wb, as opposed to the regular
w (which stand for read and write). This is because of how pickle works: it uses binary.