python，“a in b”关键字，多个a怎么样？
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python, "a in b" keyword, how about multiple a's?
提问by grigoryvp
My adventures in Python continue and my favorite books are silent again. Python offers a built-in way to test if a variable is inside an iterable object, using the 'in' keyword:
我在 Python 中的冒险仍在继续，而我最喜欢的书又沉默了。Python 提供了一种内置方法来测试变量是否在可迭代对象内，使用 'in' 关键字：
if "a" in "abrakadabra" :
print "it is definitely here"
But is it possible to test if more than one item is in the list (any one)? Currently, I'm using the syntax below, but it is kinda long:
但是是否可以测试列表中是否有多个项目（任何一个）？目前，我正在使用下面的语法，但它有点长：
if "// @in " in sTxt or "// @out " in sTxt or "// @ret " in sTxt or <10 more>
print "found."
Of course regexes can help, but using regexes will take lots of verbose of code and will not be as clear as "a in b". Are there any other Pythonic ways?
当然，正则表达式会有所帮助，但使用正则表达式会占用大量冗长的代码，而且不会像“a in b”那样清晰。有没有其他 Pythonic 方式？
回答by Markus Jarderot
alternatives = ("// @in ", "// @out ", "// @ret ")
if any(a in sTxT for a in alternatives):
print "found"
if all(a in sTxT for a in alternatives):
print "found all"
any()and all()takes an iterable and checks if any/all of them evaluate to a true value. Combine that with a generator expressions, and you can check multiple items.
any()并all()接受一个迭代并检查它们中的任何一个/全部是否评估为真值。将其与生成器表达式结合使用，您可以检查多个项目。
回答by Benjamin Peterson
any(snippet in text_body for snippet in ("hi", "foo", "bar", "spam"))
any(snippet in text_body for snippet in ("hi", "foo", "bar", "spam"))
回答by Brian
If you're testing lots of lines for the same words, it may be faster to compile them as a regular expression. eg:
如果您要为相同的单词测试很多行，将它们编译为正则表达式可能会更快。例如：
import re
words = ["// @in ", "// @out ", "// @ret "] + ["// @test%s " % i for i in range(10)]
my_regex = re.compile("|".join(map(re.escape, words)))
for line in lines_to_search:
if my_regex.search(line): print "Found match"
Some quick timing shows that this is usually faster than the any(word in theString for word in words)approach. I've tested both approaches with varying text (short/long with/without matches). Here are the results:
一些快速计时表明这通常比any(word in theString for word in words)方法更快。我已经用不同的文本（有/无匹配的短/长）测试了这两种方法。结果如下：
{ No keywords } | {contain Keywords }
short long short long
regex : 0.214 27.214 0.147 0.149
any in : 0.579 81.341 0.295 0.300
If performance doesn't matter though, the any()approach is more readable.
如果性能无关紧要，则该any()方法更具可读性。
回答by mazunki
This must be an old post, now the simplest way to do it is with a list:
这一定是一个旧帖子，现在最简单的方法是使用列表：
a = "some long text which may or may not include bononos or cabbages"
alternatives = ["apple", "banana", "riverdale"]
if a in alternatives:
print("Hm?")
回答by Esteban Küber
If you want anycheck then you would use this:
如果你想要任何检查，那么你可以使用这个：
inthere = False
checks = ('a', 'b')
for check in checks:
if check in 'abrakadabra':
inthere = True
break
If you want allcheck out you could use this:
如果你想全部退房，你可以使用这个：
inthere = True
checks = ('a', 'b')
for check in checks:
if check not in 'abrakadabra':
inthere = False
break
EDIT: Didn't know the more pythonic any(). It's probably better to use that on python.
编辑：不知道更多的 pythonic any()。在 python 上使用它可能更好。
EDIT2: Added break statements, and corrected the all-case.
EDIT2：添加了 break 语句，并更正了所有情况。
回答by allyourcode
You could also use set methods and operators:
您还可以使用set 方法和运算符：
not alternatives.isdisjoint(sTxt) # for "any"
(alternatives & sTxt) != set() # Again, the intersection is nonempty
alternatives <= sTxt # for "all"
I think these are easier to read than using the any or all, but have to convert your collections into sets. Since intersection and containment are what you care about, you might consider making them sets in the first place.
我认为这些比使用 any 或 all 更容易阅读，但必须将您的集合转换为集合。由于交叉和遏制是您关心的，您可能首先考虑将它们设置。
回答by Rory
There's no built in way in the syntax to do it. However you can use the 'any' function to make it easier as @MizardX and @Benjamin Peterson showed.
语法中没有内置的方法来做到这一点。但是，正如@MizardX 和@Benjamin Peterson 所展示的那样，您可以使用“任何”函数使其更容易。
