如何实现条件字符串格式化？

我一直在用 Python 开发一个基于文本的游戏，遇到一个实例，我想根据一组条件对字符串进行不同的格式化。

具体来说，我希望显示描述房间中物品的文本。我希望这是显示在房间的描述，当且仅当项目对象的问题是在房间对象的项目列表。按照设置的方式，我认为简单地基于条件连接字符串不会按照我想要的方式输出，对于每种情况使用不同的字符串会更好。

我的问题是，有没有基于布尔条件结果格式化字符串的 Python 方法？我可以使用 for 循环结构，但是我想知道是否有更简单的方法，类似于生成器表达式。

我正在寻找类似的东西，在字符串的形式

num = [x for x in xrange(1,100) if x % 10 == 0]

作为我的意思的一般例子:

print "At least, that's what %s told me." %("he" if gender == "male", else: "she")

我意识到这个示例不是有效的 Python，但它通常显示了我所寻找的内容。我想知道是否有任何布尔字符串格式的有效表达式，类似于上面。 在搜索了一会儿之后，我找不到任何与条件字符串格式相关的东西。我确实找到了一些关于格式字符串的文章，但这不是我要找的。

如果这样的东西确实存在，那将是非常有用的。我也愿意接受任何可能的替代方法。提前感谢你所能提供的任何帮助。

113470 次浏览
小开
最佳答案

Your code actually is valid Python if you remove two characters, the comma and the colon.

>>> gender= "male"
>>> print "At least, that's what %s told me." %("he" if gender == "male" else "she")
At least, that's what he told me.

More modern style uses .format, though:

>>> s = "At least, that's what {pronoun} told me.".format(pronoun="he" if gender == "male" else "she")
>>> s
"At least, that's what he told me."

where the argument to format can be a dict you build in whatever complexity you like.

小开

There is a conditional expression in Python which takes the form:

A if condition else B

Your example can easily be turned into valid Python by omitting just two characters:

print ("At least, that's what %s told me." %
("he" if gender == "male" else "she"))

An alternative I'd often prefer is to use a dictionary:

pronouns = {"female": "she", "male": "he"}
print "At least, that's what %s told me." % pronouns[gender]
小开

Use an f-string:

plural = ''
if num_doors != 1:
plural = 's'


print(f'Shut the door{plural}.')

Or in one line with a conditional expression (a one-line version of the if/else statement):

print(f'Shut the door{"s" if num_doors != 1 else ""}.')

Note that in this case you have to mix double " and single ' quotes because you can't use backslashes to escape quotes in the expression part of an f-string. You can still use backslashes in the outer part of an f-string, so f'{2+2}\n' is fine.


提交答案