4.1. Random Generator

  • Since numpy v1.17: BitGenerator for the PCG-64 (Parallel Congruent Generator 64 bit) pseudo-random number generator

  • Before numpy v1.17: Mersenne Twister algorithm for pseudorandom number generation

4.1.1. Pseudorandom Generator

>>> from time import time
>>>
>>>
>>> def randint(maximum=10):
...     return int(time()) % maximum
>>>
>>>
>>> randint()  
3
>>> randint()  
4
>>> randint()  
5
>>> randint()  
6

>>> from time import time
>>>
>>>
>>> def randint(maximum=10):
...     cpu_temperature = 52.4123123
...     return int(time() * cpu_temperature) % maximum
>>>
>>>
>>> randint()  
7
>>> randint()  
2
>>> randint()  
5
>>> randint()  
1

>>> from time import time
>>>
>>>
>>> def randint(maximum=10):
...     cpu_temperature = 52.4123123
...     fan_speed = 1200
...     ram_voltage = 1.42321321
...     network_crc = 9876
...     return int(time() * cpu_temperature * fan_speed * ram_voltage * network_crc) % maximum
>>>
>>>
>>> randint()  
3
>>> randint()  
0
>>> randint()  
2
>>> randint()  
8

4.1.2. Seed

  • Seed the generator

  • Using setting seed to the same value will always generate the same pseudorandom values

>>> import numpy as np
>>>
>>>
>>> np.random.seed(0)

4.1.3. Assignments

# %% 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

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Numpy Random Float
# - Difficulty: medium
# - Lines: 1
# - Minutes: 3

# %% English
# 1. Set random seed to zero
# 2. Define `result: np.ndarray` of 10 random floats
# 3. Run doctests - all must succeed

# %% Polish
# 1. Ustaw ziarno losowości na zero
# 2. Zdefiniuj `result: np.ndarray` z 10 losowymi liczbami zmiennoprzecinkowymi
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> assert result is not Ellipsis, \
'Assign result to variable: `result`'
>>> assert type(result) is np.ndarray, \
'Variable `result` has invalid type, expected: np.ndarray'

>>> result
array([0.5488135 , 0.71518937, 0.60276338, 0.54488318, 0.4236548 ,
       0.64589411, 0.43758721, 0.891773  , 0.96366276, 0.38344152])
"""

import numpy as np
np.random.seed(0)


result = ...



# %% 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

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Numpy Random Int
# - Difficulty: easy
# - Lines: 1
# - Minutes: 3

# %% English
# 1. Set random seed to zero
# 2. Define `result: np.ndarray` of size 16x16 with random integers `[0;9]` (inclusive)
# 3. Run doctests - all must succeed

# %% Polish
# 1. Ustaw ziarno losowości na zero
# 2. Zdefiniuj `result: np.ndarray` o rozmiarze 16x16 z losowymi liczbami całkowitymi `<0,9>` (włącznie)
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> assert result is not Ellipsis, \
'Assign result to variable: `result`'
>>> assert type(result) is np.ndarray, \
'Variable `result` has invalid type, expected: np.ndarray'

>>> result
array([[5, 0, 3, 3, 7, 9, 3, 5, 2, 4, 7, 6, 8, 8, 1, 6],
       [7, 7, 8, 1, 5, 9, 8, 9, 4, 3, 0, 3, 5, 0, 2, 3],
       [8, 1, 3, 3, 3, 7, 0, 1, 9, 9, 0, 4, 7, 3, 2, 7],
       [2, 0, 0, 4, 5, 5, 6, 8, 4, 1, 4, 9, 8, 1, 1, 7],
       [9, 9, 3, 6, 7, 2, 0, 3, 5, 9, 4, 4, 6, 4, 4, 3],
       [4, 4, 8, 4, 3, 7, 5, 5, 0, 1, 5, 9, 3, 0, 5, 0],
       [1, 2, 4, 2, 0, 3, 2, 0, 7, 5, 9, 0, 2, 7, 2, 9],
       [2, 3, 3, 2, 3, 4, 1, 2, 9, 1, 4, 6, 8, 2, 3, 0],
       [0, 6, 0, 6, 3, 3, 8, 8, 8, 2, 3, 2, 0, 8, 8, 3],
       [8, 2, 8, 4, 3, 0, 4, 3, 6, 9, 8, 0, 8, 5, 9, 0],
       [9, 6, 5, 3, 1, 8, 0, 4, 9, 6, 5, 7, 8, 8, 9, 2],
       [8, 6, 6, 9, 1, 6, 8, 8, 3, 2, 3, 6, 3, 6, 5, 7],
       [0, 8, 4, 6, 5, 8, 2, 3, 9, 7, 5, 3, 4, 5, 3, 3],
       [7, 9, 9, 9, 7, 3, 2, 3, 9, 7, 7, 5, 1, 2, 2, 8],
       [1, 5, 8, 4, 0, 2, 5, 5, 0, 8, 1, 1, 0, 3, 8, 8],
       [4, 4, 0, 9, 3, 7, 3, 2, 1, 1, 2, 1, 4, 2, 5, 5]])
"""

import numpy as np
np.random.seed(0)


result = ...



# %% 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

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Numpy Random Choice
# - Difficulty: medium
# - Lines: 1
# - Minutes: 3

# %% English
# 1. Set random seed to zero
# 2. Define `result: np.ndarray` with 6 random numbers
#    without repetition from `DATA`
# 3. Run doctests - all must succeed

# %% Polish
# 1. Ustaw ziarno losowości na zero
# 2. Zdefiniuj `result: np.ndarray` z 6 losowymi
#    liczbami bez powtórzeń z `DATA`
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> assert result is not Ellipsis, \
'Assign result to variable: `result`'
>>> assert type(result) is np.ndarray, \
'Variable `result` has invalid type, expected: np.ndarray'

>>> result
array([30,  5, 27, 31, 33, 38])
"""

import numpy as np
np.random.seed(0)

DATA = np.arange(1, 50)
result = ...