7.2. Methods Sort

7.2.1. SetUp

>>> import numpy as np

7.2.2. Sort

Sort vector:

>>> a = np.array([2, 3, 1])
>>> a.sort()
>>>
>>> a
array([1, 2, 3])

Sort matrix:

>>> a = np.array([[9, 7, 8],
...               [2, 3, 1],
...               [5, 6, 4]])
>>> a.sort()
>>> a
array([[7, 8, 9],
       [1, 2, 3],
       [4, 5, 6]])

Sort matrix rows:

>>> a = np.array([[9, 7, 8],
...               [2, 3, 1],
...               [5, 6, 4]])
>>>
>>> a.sort(axis=0)
>>> a
array([[2, 3, 1],
       [5, 6, 4],
       [9, 7, 8]])

Sort matrix columns:

>>> a = np.array([[9, 7, 8],
...               [2, 3, 1],
...               [5, 6, 4]])
>>>
>>> a.sort(axis=1)
>>> a
array([[7, 8, 9],
       [1, 2, 3],
       [4, 5, 6]])

7.2.3. Flip

Does not modify inplace
Returns new np.ndarray
Reverse the order of elements in an array along the given axis

Flip vector:

>>> a = np.array([1, 2, 3])
>>>
>>> np.flip(a)
array([3, 2, 1])

Flip matrix:

>>> a = np.array([[1, 2, 3],
...               [4, 5, 6]])

Flip matrix by crossline from top-left to bottom-right:

>>> np.flip(a)
array([[6, 5, 4],
       [3, 2, 1]])

Flip matrix by rows (bottom rows goes up, upper rows goes down):

>>> np.flip(a, axis=0)
array([[4, 5, 6],
       [1, 2, 3]])

Flip matrix by column (left columns from center goes right, right columns go left):

>>> np.flip(a, axis=1)
array([[3, 2, 1],
       [6, 5, 4]])

7.2.4. 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 Sort
# - Difficulty: easy
# - Lines: 2
# - Minutes: 3

# %% English
# 1. Define `result_sort` with sorted `DATA` by columns
# 2. Define `result_flip` with flipped `DATA` by rows
# 3. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj `result_sort` z posortowanym `DATA` po kolumnach
# 2. Zdefiniuj `result_flip` z flipniętym `DATA` po wierszach
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Hints
# - `.sort()` returns `None`

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

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

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

>>> result_sort
array([[44, 47, 64, 67],
       [ 9, 21, 67, 83],
       [36, 70, 87, 88]])

>>> result_flip
array([[36, 87, 70, 88],
       [67,  9, 83, 21],
       [44, 47, 64, 67]])
"""

import numpy as np


DATA = np.array([[44, 47, 64, 67],
                 [67,  9, 83, 21],
                 [36, 87, 70, 88]])

result_sort = ...
result_flip = ...