13.3. Pickle Dump
pickle.dump(object) -> filepickle.dumps(object) -> bytes
13.3.1. SetUp
>>> import pickle
13.3.2. Sequence
>>> DATA = ('Alice', 'Apricot', 30)
>>>
>>> pickle.dumps(DATA)
b'\x80\x04\x95\x17\x00\x00\x00\x00\x00\x00\x00\x8c\x05Alice\x94\x8c\x07Apricot\x94K\x1e\x87\x94.'
13.3.3. List of Sequences
>>> DATA = [
... ('firstname', 'lastname', 'age'),
... ('Alice', 'Apricot', 30),
... ('Bob', 'Blackthorn', 31),
... ('Carol', 'Corn', 32),
... ('Dave', 'Durian', 33),
... ('Eve', 'Elderberry', 34),
... ('Mallory', 'Melon', 15),
... ]
>>>
>>> pickle.dumps(DATA)
b'\x80\x04\x95\xa5\x00\x00\x00\x00\x00\x00\x00]\x94(\x8c\tfirstname\x94\x8c\x08lastname\x94\x8c\x03age\x94\x87\x94\x8c\x05Alice\x94\x8c\x07Apricot\x94K\x1e\x87\x94\x8c\x03Bob\x94\x8c\nBlackthorn\x94K\x1f\x87\x94\x8c\x05Carol\x94\x8c\x04Corn\x94K \x87\x94\x8c\x04Dave\x94\x8c\x06Durian\x94K!\x87\x94\x8c\x03Eve\x94\x8c\nElderberry\x94K"\x87\x94\x8c\x07Mallory\x94\x8c\x05Melon\x94K\x0f\x87\x94e.'
13.3.4. Mapping
>>> DATA = {'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30}
>>>
>>> pickle.dumps(DATA)
b'\x80\x04\x956\x00\x00\x00\x00\x00\x00\x00}\x94(\x8c\tfirstname\x94\x8c\x05Alice\x94\x8c\x08lastname\x94\x8c\x07Apricot\x94\x8c\x03age\x94K\x1eu.'
13.3.5. List of Mappings
>>> DATA = [
... {'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
... {'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
... {'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
... {'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
... {'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
... {'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15},
... ]
>>>
>>> pickle.dumps(DATA)
b'\x80\x04\x95\xcd\x00\x00\x00\x00\x00\x00\x00]\x94(}\x94(\x8c\tfirstname\x94\x8c\x05Alice\x94\x8c\x08lastname\x94\x8c\x07Apricot\x94\x8c\x03age\x94K\x1eu}\x94(h\x02\x8c\x03Bob\x94h\x04\x8c\nBlackthorn\x94h\x06K\x1fu}\x94(h\x02\x8c\x05Carol\x94h\x04\x8c\x04Corn\x94h\x06K u}\x94(h\x02\x8c\x04Dave\x94h\x04\x8c\x06Durian\x94h\x06K!u}\x94(h\x02\x8c\x03Eve\x94h\x04\x8c\nElderberry\x94h\x06K"u}\x94(h\x02\x8c\x07Mallory\x94h\x04\x8c\x05Melon\x94h\x06K\x0fue.'
13.3.6. List of Objects
vars()will convertobjecttodict
>>> class User:
... def __init__(self, firstname, lastname, age):
... self.firstname = firstname
... self.lastname = lastname
... self.age = age
...
... def __repr__(self):
... clsname = self.__class__.__name__
... firstname = self.firstname
... lastname = self.lastname
... age = self.age
... return f'{clsname}({firstname=}, {lastname=}, {age=})'
>>>
>>>
>>> DATA = [
... User('Alice', 'Apricot', age=30),
... User('Bob', 'Blackthorn', age=31),
... User('Carol', 'Corn', age=32),
... User('Dave', 'Durian', age=33),
... User('Eve', 'Elderberry', age=34),
... User('Mallory', 'Melon', age=15),
... ]
>>>
>>> pickle.dumps(DATA)
b'\x80\x04\x95\x03\x01\x00\x00\x00\x00\x00\x00]\x94(\x8c\x08__main__\x94\x8c\x04User\x94\x93\x94)\x81\x94}\x94(\x8c\tfirstname\x94\x8c\x05Alice\x94\x8c\x08lastname\x94\x8c\x07Apricot\x94\x8c\x03age\x94K\x1eubh\x03)\x81\x94}\x94(h\x06\x8c\x03Bob\x94h\x08\x8c\nBlackthorn\x94h\nK\x1fubh\x03)\x81\x94}\x94(h\x06\x8c\x05Carol\x94h\x08\x8c\x04Corn\x94h\nK ubh\x03)\x81\x94}\x94(h\x06\x8c\x04Dave\x94h\x08\x8c\x06Durian\x94h\nK!ubh\x03)\x81\x94}\x94(h\x06\x8c\x03Eve\x94h\x08\x8c\nElderberry\x94h\nK"ubh\x03)\x81\x94}\x94(h\x06\x8c\x07Mallory\x94h\x08\x8c\x05Melon\x94h\nK\x0fube.'
13.3.7. To File
open(file, mode='wb')for writing binary data
SetUp:
>>> DATA = [
... {'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
... {'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
... {'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
... {'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
... {'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
... {'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15},
... ]
Solution:
>>> with open('/tmp/myfile.pkl', mode='wb') as file:
... pickle.dump(DATA, file)
Result:
>>> open('/tmp/myfile.pkl', mode='rb').read()
b'\x80\x04\x95\xcd\x00\x00\x00\x00\x00\x00\x00]\x94(}\x94(\x8c\tfirstname\x94\x8c\x05Alice\x94\x8c\x08lastname\x94\x8c\x07Apricot\x94\x8c\x03age\x94K\x1eu}\x94(h\x02\x8c\x03Bob\x94h\x04\x8c\nBlackthorn\x94h\x06K\x1fu}\x94(h\x02\x8c\x05Carol\x94h\x04\x8c\x04Corn\x94h\x06K u}\x94(h\x02\x8c\x04Dave\x94h\x04\x8c\x06Durian\x94h\x06K!u}\x94(h\x02\x8c\x03Eve\x94h\x04\x8c\nElderberry\x94h\x06K"u}\x94(h\x02\x8c\x07Mallory\x94h\x04\x8c\x05Melon\x94h\x06K\x0fue.'
13.3.8. Recap
pickle.dump(object) -> filepickle.dumps(object) -> bytesopen(file, mode='wb')for writing binary data
13.3.9. Assignments
# %% About
# - Name: Pickle Dump Tuple
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% English
# 1. Define `result: bytes` with serialized `DATA`
# 2. Use `pickle` module
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zdefiniuj `result: bytes` z serializowanym `DATA`
# 2. Użyj modułu `pickle`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Example
# >>> result
# ('Alice', 'Apricot', 30)
# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> result = pickle.loads(result)
>>> assert type(result) is tuple, \
'Variable `result` has invalid type, should be tuple'
>>> from pprint import pprint
>>> pprint(result, width=79, sort_dicts=False)
('Alice', 'Apricot', 30)
"""
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`
# %% Imports
import pickle
# %% Types
result: bytes
# %% Data
DATA = ('Alice', 'Apricot', 30)
# %% Result
result = ...
# %% About
# - Name: Pickle Dump ListTuple
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% English
# 1. Define `result: bytes` with serialized `DATA`
# 2. Use `pickle` module
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zdefiniuj `result: bytes` z serializowanym `DATA`
# 2. Użyj modułu `pickle`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Example
# >>> result
# [('firstname', 'lastname', 'age'),
# ('Alice', 'Apricot', 30),
# ('Bob', 'Blackthorn', 31),
# ('Carol', 'Corn', 32),
# ('Dave', 'Durian', 33),
# ('Eve', 'Elderberry', 34),
# ('Mallory', 'Melon', 15)]
# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> result = pickle.loads(result)
>>> assert type(result) is list, \
'Variable `result` has invalid type, should be list'
>>> assert all(type(row) is tuple for row in result), \
'Variable `result` has invalid type, should be tuple'
>>> from pprint import pprint
>>> pprint(result, width=79, sort_dicts=False)
[('firstname', 'lastname', 'age'),
('Alice', 'Apricot', 30),
('Bob', 'Blackthorn', 31),
('Carol', 'Corn', 32),
('Dave', 'Durian', 33),
('Eve', 'Elderberry', 34),
('Mallory', 'Melon', 15)]
"""
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`
# %% Imports
import pickle
# %% Types
result: bytes
# %% Data
DATA = [
('firstname', 'lastname', 'age'),
('Alice', 'Apricot', 30),
('Bob', 'Blackthorn', 31),
('Carol', 'Corn', 32),
('Dave', 'Durian', 33),
('Eve', 'Elderberry', 34),
('Mallory', 'Melon', 15),
]
# %% Result
result = ...
# %% About
# - Name: Pickle Dump Dict
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% English
# 1. Define `result: bytes` with serialized `DATA`
# 2. Use `pickle` module
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zdefiniuj `result: bytes` z serializowanym `DATA`
# 2. Użyj modułu `pickle`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Example
# >>> result
# {'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30}
# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> result = pickle.loads(result)
>>> assert type(result) is dict, \
'Variable `result` has invalid type, should be dict'
>>> from pprint import pprint
>>> pprint(result, width=79, sort_dicts=False)
{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30}
"""
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`
# %% Imports
import pickle
# %% Types
result: bytes
# %% Data
DATA = {'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30}
# %% Result
result = ...
# %% About
# - Name: Pickle Dump ListDict
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% English
# 1. Define `result: bytes` with serialized `DATA`
# 2. Use `pickle` module
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zdefiniuj `result: bytes` z serializowanym `DATA`
# 2. Użyj modułu `pickle`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Example
# >>> result
# [{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
# {'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
# {'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
# {'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
# {'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
# {'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15}]
# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> result = pickle.loads(result)
>>> assert type(result) is list, \
'Variable `result` has invalid type, should be list'
>>> assert all(type(row) is dict for row in result), \
'Variable `result` has invalid type, should be dict'
>>> from pprint import pprint
>>> pprint(result, width=79, sort_dicts=False)
[{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
{'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
{'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
{'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
{'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
{'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15}]
"""
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`
# %% Imports
import pickle
# %% Types
result: bytes
# %% Data
DATA = [
{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
{'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
{'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
{'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
{'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
{'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15},
]
# %% Result
result = ...
# %% About
# - Name: Pickle Dump ListObject
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% English
# 1. Define `result: bytes` with serialized `DATA`
# 2. Use `pickle` module
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zdefiniuj `result: bytes` z serializowanym `DATA`
# 2. Użyj modułu `pickle`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Example
# >>> result
# [User(firstname='Alice', lastname='Apricot', age=30),
# User(firstname='Bob', lastname='Blackthorn', age=31),
# User(firstname='Carol', lastname='Corn', age=32),
# User(firstname='Dave', lastname='Durian', age=33),
# User(firstname='Eve', lastname='Elderberry', age=34),
# User(firstname='Mallory', lastname='Melon', age=15)]
# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> result = pickle.loads(result)
>>> assert type(result) is list, \
'Variable `result` has invalid type, should be list'
>>> assert all(type(row) is User for row in result), \
'Variable `result` has invalid type, should be User'
>>> from pprint import pprint
>>> pprint(result, width=79, sort_dicts=False)
[User(firstname='Alice', lastname='Apricot', age=30),
User(firstname='Bob', lastname='Blackthorn', age=31),
User(firstname='Carol', lastname='Corn', age=32),
User(firstname='Dave', lastname='Durian', age=33),
User(firstname='Eve', lastname='Elderberry', age=34),
User(firstname='Mallory', lastname='Melon', age=15)]
"""
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`
# %% Imports
import pickle
# %% Types
result: bytes
# %% Data
class User:
def __init__(self, firstname, lastname, age=None):
self.firstname = firstname
self.lastname = lastname
self.age = age
def __repr__(self):
clsname = self.__class__.__qualname__
arguments = ', '.join(f'{k}={v!r}' for k,v in vars(self).items())
return f'{clsname}({arguments})'
DATA = [
User('Alice', 'Apricot', age=30),
User('Bob', 'Blackthorn', age=31),
User('Carol', 'Corn', age=32),
User('Dave', 'Durian', age=33),
User('Eve', 'Elderberry', age=34),
User('Mallory', 'Melon', age=15),
]
# %% Result
result = ...
# %% About
# - Name: Pickle Dump ToFile
# - Difficulty: easy
# - Lines: 2
# - Minutes: 2
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% English
# 1. Serialize `DATA` to `FILE`
# 2. Use `pickle` module
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zserializuj `DATA` do `FILE`
# 2. Użyj modułu `pickle`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Example
# >>> result
# [{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
# {'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
# {'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
# {'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
# {'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
# {'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15}]
# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> with open(FILE, mode='rb') as file:
... result = pickle.load(file)
>>> from os import remove
>>> remove(FILE)
>>> assert type(result) is list, \
'Variable `result` has invalid type, should be list'
>>> assert all(type(row) is dict for row in result), \
'Variable `result` has invalid type, should be dict'
>>> from pprint import pprint
>>> pprint(result, width=79, sort_dicts=False)
[{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
{'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
{'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
{'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
{'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
{'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15}]
"""
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`
# %% Imports
import pickle
# %% Types
# %% Data
FILE = r'_temporary.pkl'
DATA = [
{'firstname': 'Alice', 'lastname': 'Apricot', 'age': 30},
{'firstname': 'Bob', 'lastname': 'Blackthorn', 'age': 31},
{'firstname': 'Carol', 'lastname': 'Corn', 'age': 32},
{'firstname': 'Dave', 'lastname': 'Durian', 'age': 33},
{'firstname': 'Eve', 'lastname': 'Elderberry', 'age': 34},
{'firstname': 'Mallory', 'lastname': 'Melon', 'age': 15},
]
# %% Result