格式的正则表达式在Python

Question

我有话

wordlist = ['hypothesis' , 'test' , 'results' , 'total'] 

的名单上有一句话

sentence = "These tests will benefit in the long run." 

我要检查，看看是否在wordlist的词在句子。我知道，你可以检查，看看他们是否正在使用中的一句话子：

for word in wordlist: 
    if word in sentence: 
     print word 

但是，使用子，我开始匹配不在wordlist的话，例如这里test将显示为一个子即使它是句子中的tests。我可以通过使用正则表达式来解决我的问题，但是，是否可以通过用每个新单词格式化的方式实现正则表达式，这意味着如果我想查看该单词是否在句子中，则：

for some_word_goes_in_here in wordlist: 
    if re.search('.*(some_word_goes_in_here).*', sentence): 
     print some_word_goes_in_here 

所以在这种情况下，正则表达式会将some_word_goes_in_here解释为需要搜索的模式，而不是some_word_goes_in_here的值。有没有一种方法来格式化输入some_word_goes_in_here，以便正则表达式搜索some_word_goes_in_here的值？

Answer 1

尝试使用：

if re.search(r'\b' + word + r'\b', sentence): 

\b字界限，将你的话和非单词字符之间的匹配（单词字符是任何字母，数字或下划线）。

例如，

>>> import re 
>>> wordlist = ['hypothesis' , 'test' , 'results' , 'total'] 
>>> sentence = "The total results for the test confirm the hypothesis" 
>>> for word in wordlist: 
...  if re.search(r'\b' + word + r'\b', sentence): 
...    print word 
... 
hypothesis 
test 
results 
total 

随着你的字符串：

>>> sentence = "These tests will benefit in the long run." 
>>> for word in wordlist: 
...  if re.search(r'\b' + word + r'\b', sentence): 
...   print word 
... 
>>> 

什么也没有打印

Answer 2

使用\b字边界来测试的话：

for word in wordlist: 
    if re.search(r'\b{}\b'.format(re.escape(word)), sentence): 
     print '{} matched'.format(word) 

但你也可以把这个句子分成单独的单词。使用一组单词列表将让测试更有效率：

words = set(wordlist) 
if words.intersection(sentence.split()): 
    # no looping over `words` required. 

演示：

>>> import re 
>>> wordlist = ['hypothesis' , 'test' , 'results' , 'total'] 
>>> sentence = "These tests will benefit in the long run." 
>>> for word in wordlist: 
...  if re.search(r'\b{}\b'.format(re.escape(word)), sentence): 
...   print '{} matched'.format(word) 
... 
>>> words = set(wordlist) 
>>> words.intersection(sentence.split()) 
set([]) 
>>> sentence = 'Lets test this hypothesis that the results total the outcome' 
>>> for word in wordlist: 
...  if re.search(r'\b{}\b'.format(re.escape(word)), sentence): 
...   print '{} matched'.format(word) 
... 
hypothesis matched 
test matched 
results matched 
total matched 
>>> words.intersection(sentence.split()) 
set(['test', 'total', 'hypothesis', 'results']) 

Answer 3

我会使用这样的：

words = "hypothesis test results total".split() 
# ^^^ but you can use your literal list if you prefer that 
for word in words: 
    if re.search(r'\b%s\b' % (word,), sentence): 
    print word 

您甚至可以通过加快这使用单个正则表达式：

for foundWord in re.findall(r'\b' + r'\b|\b'.join(words) + r'\b', sentence): 
    print foundWord