Chapter 10: Problem 34

When you open a file for the purpose of saving a pickled object to it, what file access mode do you use?

Short Answer

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Answer: The appropriate file access mode for saving a pickled object in Python is 'wb', which stands for "write binary." This mode allows writing binary data to the file and overwrites any existing content in the file.

Step by step solution

Introduction to pickling in Python

Pickling is a process in Python where a Python object hierarchy (like list, dictionary, or custom object) is converted into a byte stream. The process is also called serialization or flattening. By pickling and unpickling, Python objects can be stored in files and later retrieved while maintaining their original properties and states. The module in Python responsible for pickling is called "pickle."

Opening a file for pickling

To store a pickled object into a file, the file must first be opened in appropriate access mode. Generally, file access modes are used to determine how the opened file should be treated - for reading, writing, or appending. Some popular access modes are 'r' for reading, 'w' for writing, 'a' for appending, and 'b' for binary mode.

Choosing the correct file access mode for saving pickled objects

Since pickling results in a binary formatted stream, it's essential to use a binary mode when opening the file. Also, we need to store the pickled object into the file, which implies that we need a writing mode. Thus, the correct access mode for saving a pickled object to the file is 'wb', which stands for "write binary." This mode allows writing binary data to the file and overwrites any existing content in the file.

Example of pickling a Python object and saving it to a file

Here's an example using the 'pickle' module: ```python import pickle data = {"key": "value"} # Create a new or open an existing binary file in 'write binary' mode with open("data.pickle", "wb") as file: # Save the pickled object to the file pickle.dump(data, file) ``` In this example, we import the 'pickle' module and create a dictionary named 'data'. Next, we open a file called "data.pickle" using the 'with' statement and the 'wb' access mode. Finally, we save the pickled object (dictionary) into the file using the 'pickle.dump()' function.

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When you open a file for the purpose of saving a pickled object to it, what file access mode do you use?

Short Answer

Step by step solution

Introduction to pickling in Python

Opening a file for pickling

Choosing the correct file access mode for saving pickled objects

Example of pickling a Python object and saving it to a file

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