Python:检查字典中的键是否包含在字符串中 [英] Python: Check if a key in a dictionary is contained in a string

问题描述

假设我有一本字典，

mydict = { "short bread": "bread", 
           "black bread": "bread", 
           "banana cake": "cake", 
           "wheat bread": "bread" }

给出字符串"wheat bread breakfast today"，我要检查字符串中是否包含字典中的任何键.如果是这样，我想返回与该键关联的字典中的值.

Given the string "wheat bread breakfast today" I want to check if any key in my dictionary is contained in the string. If so, I want to return the value in the dictionary associated with that key.

我想为此使用列表理解.

I want to use a list comprehension for this.

这是我到目前为止所拥有的.

Here's what I have so far.

mykeys = mydict.keys()
mystring = "wheat breads breakfast today"
if any(s in string for s in mykeys):
    print("Yes")

这将按预期输出Yes.我真正想做的是使用s变量索引到mydict中.但是s在any()函数内部的作用域有限.因此，以下操作无效.

This outputs Yes as expected. What I really want to do is to use the s variable to index into mydict. But s has a limited scope inside the any() function. So the following does not work.

if any(s in mystring for s in mykeys):
    print(mydict[s])

有任何解决方法吗?非常感谢！

Any workaround? Many thanks!

推荐答案

只需循环浏览各个键并检查每个键即可.

Just loop through the keys and check each one.

for key in mydict:
    if key in mystring:
         print(mydict[key])

如果您想在列表理解中做到这一点，只需检查每次迭代中的键即可.

If you want to do it in a list comprehension, just check the key on each iteration.

[val for key,val in mydict.items() if key in mystring]

您还可以在初始循环中过滤字典键，而不是单独进行检查.

You could also filter the dictionary keys in the initial loop instead of a separate check.

for key in (key in mydict if key in mystring):
    print(mydict[key])

或者，如果您想使用filter，可以使用它.

Or you could use filter if you feel like getting functional with it.

list(map(mydict.get, filter(lambda x:x in mystring, mydict)))

或者使用过滤器的另一种方式(实际上不使用此过滤器，它非常不可读，只是在这里很有趣).

Or another way with filter (don't actually use this one, it's super unreadable and just here for fun).

list(filter(bool,[v*(k in mystring) for k,v in mydict.items()]))

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