问题：在Python中格式化多行字典的正确方法是什么？

在Python中，我想在代码中编写多行字典。有几种方法可以格式化它。我想到的是一些：

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

我知道以上任何一种在语法上都是正确的，但是我假设Python字典有一种首选的缩进和换行样式。它是什么？

注意：这不是语法问题。就我所知，以上所有都是有效的Python语句，并且彼此等效。

点击查看英文原文

In Python, I want to write a multi-line dict in my code. There are a couple of ways one could format it. Here are a few that I could think of:

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

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

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

I know that any of the above is syntactically correct, but I assume that there is one preferred indentation and line-break style for Python dicts. What is it?

Note: This is not an issue of syntax. All of the above are (as far as I know) valid Python statements and are equivalent to each other.

回答 0

我使用＃3。长列表，元组等也是如此。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，这是在不引入任何空格的情况下包括大字符串的我的首选方式（例如，如果使用三引号的多行字符串，则会得到此信息）：

data = (
    "iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAABG"
    "l0RVh0U29mdHdhcmUAQWRvYmUgSW1hZ2VSZWFkeXHJZTwAAAEN"
    "xBRpFYmctaKCfwrBSCrRLuL3iEW6+EEUG8XvIVjYWNgJdhFjIX"
    "rz6pKtPB5e5rmq7tmxk+hqO34e1or0yXTGrj9sXGs1Ib73efh1"
    "AAAABJRU5ErkJggg=="
)
点击查看英文原文

I use #3. Same for long lists, tuples, etc. It doesn’t require adding any extra spaces beyond the indentations. As always, be consistent.

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

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

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

Similarly, here’s my preferred way of including large strings without introducing any whitespace (like you’d get if you used triple-quoted multi-line strings):

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

回答 1

首先，就像史蒂文·鲁姆巴尔斯基（Steven Rumbalski）所说的那样，“ PEP8不能解决这个问题”，因此这是个人喜好问题。

我将使用与您的格式3类似但不完全相同的格式。这是我的，以及原因。

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()
点击查看英文原文

First of all, like Steven Rumbalski said, “PEP8 doesn’t address this question”, so it is a matter of personal preference.

I would use a similar but not identical format as your format 3. Here is mine, and why.

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()

回答 2

由于您的键是字符串，并且因为我们在谈论可读性，所以我更喜欢： 

mydict = dict(
    key1 = 1,
    key2 = 2,
    key3 = 3,
)
点击查看英文原文

Since your keys are strings and since we are talking about readability, I prefer : 

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

回答 3

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。

这是python-beautifier-www.cleancss.com/python-beautify，可立即将您的数据转换为可自定义的样式。

点击查看英文原文

Usually, if you have big python objects it’s quite hard to format them. I personally prefer using some tools for that.

Here is python-beautifier – www.cleancss.com/python-beautify that instantly turns your data into customizable style.

回答 4

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(",", "")))
点击查看英文原文 
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(",", "")))

回答 5

根据我在教程和其他方面的经验，似乎总是首选2号，但这是个人喜好选择，而不是其他任何事情。

点击查看英文原文

From my experience with tutorials, and other things number 2 always seems preferred, but it’s a personal preference choice more than anything else.

回答 6

通常，您不会在最后一个输入项后加入逗号，但Python会为您更正。

点击查看英文原文

Generally, you would not include the comma after the final entry, but Python will correct that for you.

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