• Ternary Operator - a if CONDITION else b

  • Conditional Expression - True if CONDITION else False

  • Shorthand Expressions - result = CONDITION

11.5.1. Recap

>>> age = 7
>>>
>>> if age < 18:
...     status = 'junior'
... else:
...     status = 'senior'

11.5.2. Ternary Operator

  • a if CONDITION else b

>>> age = 7
>>> status = 'junior' if age < 18 else 'senior'

11.5.3. Conditional Expression

  • True if CONDITION else False

>>> age = 7
>>> is_junior = True if age < 18 else False

11.5.4. Shorthand Expressions

  • result = CONDITION

>>> age = 7
>>> is_junior = age < 18

11.5.5. Use Case - 1

SetUp:

>>> username = 'alice'
>>> password = 'secret'

Using normal if:

>>> if username == 'alice' and password == 'secret':
...     print('Access Granted')
...
Access Granted

Using expression 1:

>>> valid_username = (username == 'alice')
>>> valid_password = (password == 'secret')
>>>
>>> if valid_username and valid_password:
...     print('Access Granted')
...
Access Granted

Using expression 2:

>>> valid_username = (username == 'alice')
>>> valid_password = (password == 'secret')
>>> valid_credentials = valid_username and valid_password
>>>
>>> if valid_credentials:
...     print('Access Granted')
...
Access Granted

11.5.6. Use Case - 2

  • Is numeric

SetUp:

>>> # Simulate user response '10' when prompted by input()
>>> from unittest.mock import Mock
>>> input = Mock(side_effect=['10'])

Usage:

>>> age = input('What is your age?: ')   # input: '10'
>>> age = float(age) if age.isnumeric() else None
>>>
>>> print(age)
10.0

11.5.7. Use Case - 3

  • Even/odd

>>> number = 3
>>> is_even = (number % 2 == 0 )
>>>
>>> print(is_even)
False

11.5.8. Use Case - 4

  • Astronaut/Cosmonaut

>>> country = 'Russia'
>>> job = 'astronaut' if country == 'USA' else 'cosmonaut'
>>>
>>> print(job)
cosmonaut

11.5.9. Use Case - 5

  • IPv4/IPv6

>>> ip = '127.0.0.1'
>>> protocol = 'IPv4' if '.' in ip else 'IPv6'
>>>
>>> print(protocol)
IPv4

>>> ip = 'fe80::aede:48ff:fe01:1133'
>>> protocol = 'IPv4' if '.' in ip else 'IPv6'
>>>
>>> print(protocol)
IPv6

11.5.10. Assignments

# %% About
# - Name: Conditional Expression Junior/Senior
# - 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 variable `result: str` with value:
#    - 'junior' - if `AGE` is below 18
#    - 'senior' - if `AGE` is 18 or above
# 2. Use ternary operator (`a if CONDITION else b`)
# 3. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj zmienną `result: str` z wartością:
#    - 'junior' - jeżeli `AGE` jest poniżej 18 lat
#    - 'senior' - jeżeli `AGE` jest 18 lat lub więcej
# 2. Użyj ternary operator (`a if CONDITION else b`)
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Expected
# >>> result
# 'senior'

# %% Hints
# - `<`

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0

>>> assert sys.version_info >= (3, 9), \
'Python has an is invalid version; expected: `3.9` or newer.'

>>> from pprint import pprint

>>> assert 'result' in globals(), \
'Variable `result` is not defined; assign result of your program to it.'

>>> assert result is not Ellipsis, \
'Variable `result` has an invalid value; assign result of your program to it.'

>>> assert type(result) is str, \
'Variable `result` has an invalid type; expected: `str`.'

>>> assert result in {'junior', 'senior'}, \
'Variable `result` should be either junior or senior'

>>> pprint(result)
'senior'
"""

# %% 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

# %% Types
result: str

# %% Data
AGE = 30

# %% Result
result = ...


# %% About
# - Name: Conditional Expression IPv4/IPv6
# - 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. To `result: str` assign whether `IP_ADDRESS` is IPv4 or IPv6 protocol:
#    - `IPv4` if dot `.` is in the IP address
#    - `IPv6` if dot `.` is not in the IP address
# 2. Use ternary operator (`a if CONDITION else b`)
# 3. Run doctests - all must succeed

# %% Polish
# 1. Użytkownik podał adres IP
# 1. Do `result: str` przypisz czy `IP_ADDRESS` jest protokołu IPv4 czy IPv6:
#    - `IPv4` jeżeli jest kropka `.` w adresie IP
#    - `IPv6` jeżeli kropki nie ma
# 2. Użyj ternary operator (`a if CONDITION else b`)
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Expected
# >>> result
# 'IPv4'

# %% Hints
# - `in`
# - In IPv6 address there is no dot `.`
# - IPv4 example: `127.0.0.1`
# - IPv6 example: `2001:0db8:85a3:0000:0000:8a2e:0370:7334`

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0

>>> assert sys.version_info >= (3, 9), \
'Python has an is invalid version; expected: `3.9` or newer.'

>>> assert 'result' in globals(), \
'Variable `result` is not defined; assign result of your program to it.'

>>> assert result is not Ellipsis, \
'Variable `result` has an invalid value; assign result of your program to it.'

>>> assert type(result) is str, \
'Variable `result` has an invalid type; expected: `str`.'

>>> assert result in ('IPv4', 'IPv6'), \
'Variable `result` must be either `IPv4` or `IPv6`'
"""

# %% 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

# %% Types
result: str

# %% Data
IP_ADDRESS = '127.0.0.1'

# %% Result
result = ...


# %% About
# - Name: Conditional Expression IsDigit
# - 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. Check if variable `NUMBER` is a digit (numeric value between 0 and 9)
# 2. Define variable `result` with the result
# 3. Use shorthand expression (`result = CONDITION`)
# 4. Run doctests - all must succeed

# %% Polish
# 1. Sprawdź czy zmienna `NUMBER` jest cyfrą (wartość liczbową między 0 a 9)
# 2. Zdefiniuj zmienną `result` z wynikiem
# 3. Użyj wyrażenia skróconego (`result = CONDITION`)
# 4. Uruchom doctesty - wszystkie muszą się powieść

# %% Expected
# >>> result
# True

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0

>>> assert sys.version_info >= (3, 9), \
'Python has an is invalid version; expected: `3.9` or newer.'

>>> assert 'result' in globals(), \
'Variable `result` is not defined; assign result of your program to it.'

>>> assert result is not Ellipsis, \
'Variable `result` has an invalid value; assign result of your program to it.'

>>> assert type(result) is bool, \
'Variable `result` has an invalid type; expected: `bool`.'

>>> result
True
"""

# %% 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

# %% Types
result: bool

# %% Data
NUMBER = 7

# %% Result
result = ...