The itertools is a built-in module in Python 3 and is helpful for us to use a more pythonic way to manipulate the iterables (e.g., list, set, tuple, etc.).
Another advantage of itertools is it also returns the generator type instances that have benefits of lazy evaluation from all of its methods.
In this section, we will discuss the first part of itertools. The methods in this part all return a generator that generates an infinite number of items and won't stop.
This table takes Python documentation #count as reference..
| Arguments | Results | Example |
|---|---|---|
start, [step=1] |
start, start+step, start+2step, ... | count(2.5, 0.5) = 2.5 3.0 3.5 4.0... |
from itertools import count
gen = count(2.5, 0.5)
for x in gen:
print(x)
# 2.5, 3.0, 3.5, 4.0, ... non-stopThis table takes Python documentation #cycle as reference.
| Arguments | Results | Example |
|---|---|---|
p (iterable) |
p[0], p[1], ... p[-1], p[0], p[1]... | cycle([1, 2, 3]) = 1 2 3 1 2 ... |
from itertools import cycle
gen = cycle([1, 2, 3])
for x in gen:
print(x)
# 1, 2, 3, 1, 2, ... non-stopThis table takes Python documentation #repeat as reference.
| Arguments | Results | Example |
|---|---|---|
item, [n=None] |
item, item, item, … endlessly or up to n times | repeat(Cat(), 2) = Cat(), Cat() |
from itertools import repeat
class Cat:
...
gen = repeat(Cat(), 2)
for cat in gen:
print(cat)
# <__main__.Cat object at 0x0000019AC1C5D348>
# <__main__.Cat object at 0x0000019AC1C5D348>| Article | Link |
|---|---|
| Python documentation - itertools | https://docs.python.org/3/library/itertools.html |
| Python Tutorial: Itertools Module - Iterator Functions for Efficient Looping | https://www.youtube.com/watch?v=Qu3dThVy6KQ |
| Python 好用模組介紹 - itertools & more-itertools | https://myapollo.com.tw/zh-tw/python-itertools-more-itertools/ |
| Python標準庫之itertools庫的使用方法 | https://codertw.com/%E7%A8%8B%E5%BC%8F%E8%AA%9E%E8%A8%80/364249/ |