检查单词是否在元组列表中

Question

I'm wondering how I can efficiently check whether a value is inside a given list of tuples. Say I have a list of:

("the", 1)
("check", 1)
("brown, 2)
("gary", 5)

how can I check whether a given word is inside the list, ignoring the second value of the tuples? If it was just a word I could use

if "the" in wordlist:
   #...

but this will not work, is there something along the line this i can do?

if ("the", _) in wordlist:
   #...

Answer 1

可以使用哈希

>>> word in dict(list_of_tuples)

Answer 2

Use any :

if any(word[0] == 'the' for word in wordlist):
    # do something

Answer 3

for tupl in wordlist:
    if 'the' in tupl:
        # ...

Answer 4

Lookup of the word in the list will be O(n) time complexity, so the more words in the list, the slower find will work. To speed up you may sort a list by word as a key alphabeticaly and then use binary search - search of the word becomes log(N) complexity, but the most efficient way is to use hashing with the set structure:

'the' in set((word for word, _ in a))

O(1), independent of how many words are in the set. BTW, it guarantees that only one instance of the word is inside the structure, while list can hold as many "the" as many you append. Set should be constructed once, add words with the .add method(add new word is O(1) complexity too)

Answer 5

words,scores = zip(*wordlist)

将单词列表拆分为单词列表和分数列表

print "the" in words