更简短的是:

info = data[:75] + (data[75:] and '..')

这里我使用的是文本包。缩短并处理更多的边缘情况。也包括最后一个单词的一部分，以防这个单词超过最大宽度的50%。

import textwrap


def shorten(text: str, width=30, placeholder="..."):
    """Collapse and truncate the given text to fit in the given width.

    The text first has its whitespace collapsed. If it then fits in the *width*, it is returned as is.
    Otherwise, as many words as possible are joined and then the placeholder is appended.
    """
    if not text or not isinstance(text, str):
        return str(text)
    t = text.strip()
    if len(t) <= width:
        return t

    # textwrap.shorten also throws ValueError if placeholder too large for max width
    shorten_words = textwrap.shorten(t, width=width, placeholder=placeholder)

    # textwrap.shorten doesn't split words, so if the text contains a long word without spaces, the result may be too short without this word.
    # Here we use a different way to include the start of this word in case shorten_words is less than 50% of `width`
    if len(shorten_words) - len(placeholder) < (width - len(placeholder)) * 0.5:
        return t[:width - len(placeholder)].strip() + placeholder
    return shorten_words

测试:

>>> shorten("123 456", width=7, placeholder="...")
'123 456'
>>> shorten("1 23 45 678 9", width=12, placeholder="...")
'1 23 45...'
>>> shorten("1 23 45 678 9", width=10, placeholder="...")
'1 23 45...'
>>> shorten("01 23456789", width=10, placeholder="...")
'01 2345...'
>>> shorten("012 3 45678901234567", width=17, placeholder="...")
'012 3 45678901...'
>>> shorten("1 23 45 678 9", width=9, placeholder="...")
'1 23...'
>>> shorten("1 23456", width=5, placeholder="...")
'1...'
>>> shorten("123 456", width=5, placeholder="...")
'12...'
>>> shorten("123 456", width=6, placeholder="...")
'123...'
>>> shorten("12 3456789", width=9, placeholder="...")
'12 345...'
>>> shorten("   12 3456789    ", width=9, placeholder="...")
'12 345...'
>>> shorten('123 45', width=4, placeholder="...")
'1...'
>>> shorten('123 45', width=3, placeholder="...")
'...'
>>> shorten("123456", width=3, placeholder="...")
'...'
>>> shorten([1], width=9, placeholder="...")
'[1]'
>>> shorten(None, width=5, placeholder="...")
'None'
>>> shorten("", width=9, placeholder="...")
''

假设string是我们希望截断的字符串，而nchars是输出字符串中所需的字符数。

stryng = "sadddddddddddddddddddddddddddddddddddddddddddddddddd"
nchars = 10

我们可以像下面这样截断字符串:

def truncate(stryng:str, nchars:int):
    return (stryng[:nchars - 6] + " [...]")[:min(len(stryng), nchars)]

某些测试用例的结果如下所示:

s = "sadddddddddddddddddddddddddddddd!"
s = "sa" + 30*"d" + "!"

truncate(s, 2)                ==  sa
truncate(s, 4)                ==  sadd
truncate(s, 10)               ==  sadd [...]
truncate(s, len(s)//2)        ==  sadddddddd [...]

我的解决方案为上面的测试用例产生了合理的结果。

但一些病理病例如下:

一些病理病例!

truncate(s, len(s) - 3)()       ==  sadddddddddddddddddddddd [...]
truncate(s, len(s) - 2)()       ==  saddddddddddddddddddddddd [...]
truncate(s, len(s) - 1)()       ==  sadddddddddddddddddddddddd [...]
truncate(s, len(s) + 0)()       ==  saddddddddddddddddddddddddd [...]
truncate(s, len(s) + 1)()       ==  sadddddddddddddddddddddddddd [...
truncate(s, len(s) + 2)()       ==  saddddddddddddddddddddddddddd [..
truncate(s, len(s) + 3)()       ==  sadddddddddddddddddddddddddddd [.
truncate(s, len(s) + 4)()       ==  saddddddddddddddddddddddddddddd [
truncate(s, len(s) + 5)()       ==  sadddddddddddddddddddddddddddddd 
truncate(s, len(s) + 6)()       ==  sadddddddddddddddddddddddddddddd!
truncate(s, len(s) + 7)()       ==  sadddddddddddddddddddddddddddddd!
truncate(s, 9999)()             ==  sadddddddddddddddddddddddddddddd!

值得注意的是,

当字符串包含换行字符(\n)时，可能会出现问题。 当nchars > len(s)时，我们应该打印字符串s，而不是试图打印“[…]”

下面是更多的代码:

import io

class truncate:
    """
        Example of Code Which Uses truncate:
        ```
            s = "\r<class\n 'builtin_function_or_method'>"
            s = truncate(s, 10)()
            print(s)
                    ```
                Examples of Inputs and Outputs:
                        truncate(s, 2)()   ==  \r
                        truncate(s, 4)()   ==  \r<c
                        truncate(s, 10)()  ==  \r<c [...]
                        truncate(s, 20)()  ==  \r<class\n 'bu [...]
                        truncate(s, 999)() ==  \r<class\n 'builtin_function_or_method'>
                    ```
                Other Notes:
                    Returns a modified copy of string input
                    Does not modify the original string
            """
    def __init__(self, x_stryng: str, x_nchars: int) -> str:
        """
        This initializer mostly exists to sanitize function inputs
        """
        try:
            stryng = repr("".join(str(ch) for ch in x_stryng))[1:-1]
            nchars = int(str(x_nchars))
        except BaseException as exc:
            invalid_stryng =  str(x_stryng)
            invalid_stryng_truncated = repr(type(self)(invalid_stryng, 20)())

            invalid_x_nchars = str(x_nchars)
            invalid_x_nchars_truncated = repr(type(self)(invalid_x_nchars, 20)())

            strm = io.StringIO()
            print("Invalid Function Inputs", file=strm)
            print(type(self).__name__, "(",
                  invalid_stryng_truncated,
                  ", ",
                  invalid_x_nchars_truncated, ")", sep="", file=strm)
            msg = strm.getvalue()

            raise ValueError(msg) from None

        self._stryng = stryng
        self._nchars = nchars

    def __call__(self) -> str:
        stryng = self._stryng
        nchars = self._nchars
        return (stryng[:nchars - 6] + " [...]")[:min(len(stryng), nchars)]

       >>> info = lambda data: len(data)>10 and data[:10]+'...' or data
       >>> info('sdfsdfsdfsdfsdfsdfsdfsdfsdfsdfsdf')
           'sdfsdfsdfs...'
       >>> info('sdfsdf')
           'sdfsdf'
       >>> 

简单而简短的helper函数:

def truncate_string(value, max_length=255, suffix='...'):
    string_value = str(value)
    string_truncated = string_value[:min(len(string_value), (max_length - len(suffix)))]
    suffix = (suffix if len(string_value) > max_length else '')
    return string_truncated+suffix

使用例子:

# Example 1 (default):

long_string = ""
for number in range(1, 1000): 
    long_string += str(number) + ','    

result = truncate_string(long_string)
print(result)


# Example 2 (custom length):

short_string = 'Hello world'
result = truncate_string(short_string, 8)
print(result) # > Hello... 


# Example 3 (not truncated):

short_string = 'Hello world'
result = truncate_string(short_string)
print(result) # > Hello world

刚刚收到的消息:

n = 8
s = '123'
print  s[:n-3] + (s[n-3:], '...')[len(s) > n]
s = '12345678'
print  s[:n-3] + (s[n-3:], '...')[len(s) > n]
s = '123456789'     
print  s[:n-3] + (s[n-3:], '...')[len(s) > n]
s = '123456789012345'
print  s[:n-3] + (s[n-3:], '...')[len(s) > n]

123
12345678
12345...
12345...