在 Python 中格式化多行 dict 的正确方法是什么？

Question

在 Python 中，我想在我的代码中编写一个多行字典。有几种方法可以格式化它。以下是我能想到的一些：

1. mydict = { "key1": 1,
              "key2": 2,
              "key3": 3, }
   

2. mydict = { "key1": 1,
              "key2": 2,
              "key3": 3,
            }
   

3. mydict = {
       "key1": 1,
       "key2": 2,
       "key3": 3,
   }
   

我知道以上任何一项在语法上都是正确的，但我假设 Python dicts 有一种首选的缩进和换行样式。这是什么？

注意：这不是语法问题。以上所有内容（据我所知）都是有效的 Python 语句，并且彼此等价。

Answer 1

我使用#3。对于长列表、元组等也是如此。它不需要在缩进之外添加任何额外的空格。一如既往，保持一致。

mydict = {
    "key1": 1,
    "key2": 2,
    "key3": 3,
}

mylist = [
    (1, 'hello'),
    (2, 'world'),
]

nested = {
    a: [
        (1, 'a'),
        (2, 'b'),
    ],
    b: [
        (3, 'c'),
        (4, 'd'),
    ],
}

同样，这是我在不引入任何空格的情况下包含大字符串的首选方式（就像使用三引号多行字符串时一样）：

data = (
    "iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAABG"
    "l0RVh0U29mdHdhcmUAQWRvYmUgSW1hZ2VSZWFkeXHJZTwAAAEN"
    "xBRpFYmctaKCfwrBSCrRLuL3iEW6+EEUG8XvIVjYWNgJdhFjIX"
    "rz6pKtPB5e5rmq7tmxk+hqO34e1or0yXTGrj9sXGs1Ib73efh1"
    "AAAABJRU5ErkJggg=="
)

Answer 2

首先，就像 Steven Rumbalski 所说，“PEP8 没有解决这个问题”，所以这是个人喜好问题。

我会使用与您的格式 3 相似但不相同的格式。这是我的，以及为什么。

my_dictionary = { # Don't think dict(...) notation has more readability
    "key1": 1, # Indent by one press of TAB (i.e. 4 spaces)
    "key2": 2, # Same indentation scale as above
    "key3": 3, # Keep this final comma, so that future addition won't show up as 2-lines change in code diff
    } # My favorite: SAME indentation AS ABOVE, to emphasize this bracket is still part of the above code block!
the_next_line_of_code() # Otherwise the previous line would look like the begin of this part of code

bad_example = {
               "foo": "bar", # Don't do this. Unnecessary indentation wastes screen space
               "hello": "world" # Don't do this. Omitting the comma is not good.
} # You see? This line visually "joins" the next line when in a glance
the_next_line_of_code()

btw_this_is_a_function_with_long_name_or_with_lots_of_parameters(
    foo='hello world',  # So I put one parameter per line
    bar=123,  # And yeah, this extra comma here is harmless too;
              # I bet not many people knew/tried this.
              # Oh did I just show you how to write
              # multiple-line inline comment here?
              # Basically, same indentation forms a natural paragraph.
    ) # Indentation here. Same idea as the long dict case.
the_next_line_of_code()

# By the way, now you see how I prefer inline comment to document the very line.
# I think this inline style is more compact.
# Otherwise you will need extra blank line to split the comment and its code from others.

some_normal_code()

# hi this function is blah blah
some_code_need_extra_explanation()

some_normal_code()

Answer 3

由于您的键是字符串，而且我们谈论的是可读性，所以我更喜欢：

mydict = dict(
    key1 = 1,
    key2 = 2,
    key3 = 3
)

Answer 4

通常，如果您有大型 python 对象，则很难格式化它们。我个人更喜欢为此使用一些工具。

这里是python-beautifier - www.cleancss.com/python-beautify，它可以立即将您的数据转换为可自定义的样式。

Answer 5

dict(rank = int(lst[0]),
                grade = str(lst[1]),
                channel=str(lst[2])),
                videos = float(lst[3].replace(",", " ")),
                subscribers = float(lst[4].replace(",", "")),
                views = float(lst[5].replace(",", "")))

Answer 6

根据我对教程的经验，第 2 项似乎总是首选，但这是个人偏好选择。

Answer 7

通常，您不会在最后输入后包含逗号，但 Python 会为您更正。