"有没有办法在 Python 的字典中设置默认值？"

Question

I wnat to know if there is a way to have a default value in a dictionary (without using the get function), so that:我想知道是否有办法在字典中设置默认值（不使用 get 函数），这样：

dict colors = {
"Black":(0, 0, 0),
"White":(255, 255, 255),
default:(100, 100, 100)
};

paint(colors["Blue"]);  # Paints the default value (Grey) onto the screen

Answer 1

You can use a defaultdict<\/code> .您可以使用defaultdict<\/code> 。

from collections import defaultdict

colors = defaultdict(lambda: (100, 100, 100))

colors["Black"] = (0, 0, 0),
colors["White"] = (255, 255, 255)

# Prints (0, 0, 0), because "Black" is mapped to (0, 0, 0) in the dictionary.
print(colors["Black"]) 

# Prints (100, 100, 100), because "Blue" is not a key in the dictionary.
print(d["Blue"])

Answer 2

Check out the collections.defaultdict type ( https:\/\/docs.python.org\/3\/library\/collections.html#collections.defaultdict<\/a> ):查看 collections.defaultdict 类型（ https:\/\/docs.python.org\/3\/library\/collections.html#collections.defaultdict<\/a> ）：

The first argument provides the initial value for the default_factory attribute;第一个参数提供 default_factory 属性的初始值； it defaults to None.它默认为无。 All remaining arguments are treated the same as if they were passed to the dict constructor, including keyword arguments.所有剩余的参数都被视为与传递给 dict 构造函数一样，包括关键字参数。
<\/blockquote>

Your code would use it like this:您的代码将像这样使用它：
 from collections import defaultdict colors = defaultdict(lambda: (100, 100, 100), { "Black":(0, 0, 0), "White":(255, 255, 255), }) print(colors['Blue'])<\/code><\/pre>"

"有没有办法在 Python 的字典中设置默认值？"

问题描述

2 个解决方案

解决方案1
5 已采纳 2022-02-06 02:49:04

解决方案2
2 2022-02-06 02:50:24

"有没有办法在 Python 的字典中设置默认值？"

问题描述

2 个解决方案

解决方案1 5 已采纳 2022-02-06 02:49:04

解决方案2 2 2022-02-06 02:50:24

解决方案1
5 已采纳 2022-02-06 02:49:04

解决方案2
2 2022-02-06 02:50:24