pickle dump with code examples

Pickling is the process of converting a Python object hierarchy into a byte stream. The byte stream can then be saved to a file or sent over a network. The opposite process, loading the byte stream back into a Python object hierarchy, is called unpickling.

The pickle module in Python provides the ability to pickle and unpickle Python objects. One of the most commonly used functions in the pickle module is the dump function. The dump function is used to pickle an object and save it to a file-like object.

Here is an example of how to use the dump function to pickle an object and save it to a file:

import pickle

data = {'a': [1, 2.0, 3, 4+6j],
         'b': ("character string", b"byte string"),
         'c': {None, True, False}}

with open('data.pickle', 'wb') as f:
    pickle.dump(data, f)

In this example, we are pickling a dictionary containing different types of data, such as lists, tuples, and sets. The dump function is used to pickle the data and save it to a file named 'data.pickle' in write binary mode 'wb'.

You can also use dump function to pickle an object and save it to a file-like object, such as a io.BytesIO object:

import io
import pickle

data = {'a': [1, 2.0, 3, 4+6j],
         'b': ("character string", b"byte string"),
         'c': {None, True, False}}

file = io.BytesIO()
pickle.dump(data, file)

You can also specify protocol in dump function, the protocol version used is pickle.HIGHEST_PROTOCOL by default.

import io
import pickle

data = {'a': [1, 2.0, 3, 4+6j],
         'b': ("character string", b"byte string"),
         'c': {None, True, False}}

file = io.BytesIO()
pickle.dump(data, file, protocol=pickle.DEFAULT_PROTOCOL)

It's important to note that the dump function does not return anything. The pickled data is saved directly to the file or file-like object that is passed as the second argument. To load the pickled data, you can use the load function from the pickle module.

In short, the dump function from the pickle module can be used to pickle an object and save it to a file or file-like object. It's a powerful tool for serializing Python objects, and it can be used to save data to disk or transmit it over a network.

Pickling can be used to save complex Python objects, such as classes, functions, and even modules. However, it is important to be aware that not all Python objects can be pickled. For example, file objects, socket objects and some other objects that are not easily serializable cannot be pickled.

In addition to the dump function, the pickle module also provides a dumps function, which can be used to pickle an object and return the resulting byte stream as a bytes object. Here's an example:

import pickle

data = {'a': [1, 2.0, 3, 4+6j],
         'b': ("character string", b"byte string"),
         'c': {None, True, False}}

pickled_data = pickle.dumps(data)

In this example, the dumps function is used to pickle the data, which is stored in the variable data, and return the resulting byte stream as a bytes object, which is stored in the variable pickled_data.

The loads function can be used to unpickle a byte stream and convert it back into a Python object. Here's an example:

import pickle

pickled_data = b'\x80\x04\x95\x0c\x00\x00\x00\x00\x00\x00\x00\x8c\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x
## Popular questions 
1. What is the purpose of the `dump` function in the pickle module?
- The `dump` function in the pickle module is used to pickle an object and save it to a file-like object. It is a powerful tool for serializing Python objects, and it can be used to save data to disk or transmit it over a network.

2. What is the difference between the `dump` and `dumps` functions in the pickle module?
- The `dump` function is used to pickle an object and save it to a file-like object, while the `dumps` function is used to pickle an object and return the resulting byte stream as a bytes object.

3. What types of objects can be pickled?
- Most built-in Python types such as lists, dictionaries, tuples, and strings can be pickled. Additionally, classes, functions, and even modules can be pickled. However, it is important to be aware that not all Python objects can be pickled, such as file objects, socket objects, and some other objects that are not easily serializable.

4. How can I unpickle a byte stream and convert it back into a Python object?
- The `loads` function from the pickle module can be used to unpickle a byte stream and convert it back into a Python object. For example:

import pickle

pickled_data = b'\x80\x04\x95\x0c\x00\x00\x00\x00\x00\x00\x00\x8c\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00

Tag

Serialization.