[英]What is the meaning of set[…] in Python
I'm pretty new to programming and python.我对编程和 python 很陌生。
As far as I know, for the initialization of the set function you use set()
for an empty set, and {... }
to initialize elements as a set.据我所知,对于集合 function 的初始化,您将
set()
用于空集,并使用{... }
将元素初始化为集合。 In an example code, I saw set[X]
.在示例代码中,我看到了
set[X]
。 What is the meaning of the square brackets used in set?集合中使用的方括号是什么意思?
This is the example code:这是示例代码:
def example_function(x: set[A], y: set[B]) -> set[tuple[A, B]]:
res = set()
for i in x:
for j in y:
res.add((i, j))
return res
It's a type hint , in this example, we use type hint For collections, the type of the collection item is in brackets.这是一个类型提示,在这个例子中,我们使用类型提示对于 collections,集合项的类型在括号中。
# Python 3.9
# For collections, the type of the collection item is in brackets
int_list: list[int] = [1]
int_set: set[int] = {6, 7}
# Python 3.8 and earlier, the name of the collection type is
# capitalized, and the type is imported from 'typing'
from typing import List, Set, Dict, Tuple, Optional
int_list: List[int] = [1]
int_set: Set[int] = {6, 7}
This is just a parameterising the functions and variable annotations to say that the function needs two arguments, namely x
and y
which are of type set
(build from A and B respectively) and it returns back a set consisting of tuples built by mixing set[A]
set[B]
这只是对函数和变量注释进行参数化,以说明 function 需要两个 arguments,即
x
和y
,它们是set
类型(分别从 A 和 B 构建),它返回一个由混合集合构建的元组组成的set[A]
set[B]
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