5.3. Range

5.3.1. Rationale

• Return sequence of numbers

• It is not a generator

• Generator (lazy evaluated)

• Built-in

5.3.2. Syntax

• range([start], <stop>, [step])

• optional start, inclusive, default: 0

• required stop, exclusive,

• optional step, default: 1

5.3.3. Problem

>>> i = 0
>>> result = []
>>>
>>> while i < 3:
...     result.append(i)
...     i += 1
>>>
>>> result
[0, 1, 2]

5.3.4. Solution

>>> result = range(0,3)
>>>
>>> list(result)
[0, 1, 2]

5.3.5. Lazy Evaluation

>>> for i in range(0,3):
...     print(i)
0
1
2

5.3.6. Itertools

• Learn more at https://docs.python.org/3/library/itertools.html

• More information in Itertools

• itertools.count(start=0, step=1)

>>> from itertools import count
>>>
>>>
>>> result = count(3, 2)
>>>
>>> next(result)
3
>>> next(result)
5
>>> next(result)
7

5.3.7. Assignments

Code 5.50. Solution

"""
* Assignment: Idioms Range Impl
* Complexity: medium
* Lines of code: 25 lines
* Time: 21 min

English:
    1. Use data from "Given" section (see below)
    2. Define function `myrange` with parameters: `start`, `stop`, `step`
    3. Write own implementation of a built-in `myrange(start, stop, step)` function
    4. How to implement passing only stop argument (`myrange(start=0, stop=???, step=1)`)?
    5. All tests must pass
    6. Compare result with "Tests" section (see below)

Polish:
    1. Użyj danych z sekcji "Given" (patrz poniżej)
    2. Zdefiniuj funkcję `myrange` z parametrami: `start`, `stop`, `step`
    3. Zaimplementuj własne rozwiązanie wbudowanej funkcji `myrange(start, stop, step)`
    4. Jak zaimplementować możliwość podawania tylko końca (`myrange(start=0, stop=???, step=1)`)?
    5. Wszystkie testy muszą przejść
    6. Porównaj wyniki z sekcją "Tests" (patrz poniżej)

Hint:
    * use `*args` and `**kwargs`
    * `if len(args) == ...`

Tests:
    >>> from inspect import isfunction
    >>> assert isfunction(myrange)

    >>> myrange(0, 10, 2)
    [0, 2, 4, 6, 8]

    >>> myrange(0, 5)
    [0, 1, 2, 3, 4]

    >>> myrange(5)
    [0, 1, 2, 3, 4]

    >>> myrange()
    Traceback (most recent call last):
    ValueError: Invalid arguments

    >>> myrange(1,2,3,4)
    Traceback (most recent call last):
    ValueError: Invalid arguments

    >>> myrange(stop=2)
    Traceback (most recent call last):
    TypeError: myrange() takes no keyword arguments

    >>> myrange(start=1, stop=2)
    Traceback (most recent call last):
    TypeError: myrange() takes no keyword arguments

    >>> myrange(start=1, stop=2, step=2)
    Traceback (most recent call last):
    TypeError: myrange() takes no keyword arguments
"""