如何检查数组中的任何字符串是否存在于另一个字符串中?
例如:
a = ['a', 'b', 'c']
s = "a123"
if a in s:
print("some of the strings found in s")
else:
print("no strings found in s")
我如何替换如果a在s:行得到适当的结果?
当前回答
的元素上进行迭代。
a = ['a', 'b', 'c']
str = "a123"
found_a_string = False
for item in a:
if item in str:
found_a_string = True
if found_a_string:
print "found a match"
else:
print "no match found"
其他回答
在另一个字符串列表中查找多个字符串的一种紧凑方法是使用set.intersection。这比大型集或列表中的列表理解执行得快得多。
>>> astring = ['abc','def','ghi','jkl','mno']
>>> bstring = ['def', 'jkl']
>>> a_set = set(astring) # convert list to set
>>> b_set = set(bstring)
>>> matches = a_set.intersection(b_set)
>>> matches
{'def', 'jkl'}
>>> list(matches) # if you want a list instead of a set
['def', 'jkl']
>>>
如果a或str中的字符串变长，您应该小心。简单的解决方案是O(S*(A^2))，其中S是str的长度，A是A中所有字符串长度的总和。要获得更快的解决方案，请查看用于字符串匹配的Aho-Corasick算法，该算法在线性时间O(S+A)内运行。
如果您想要单词的精确匹配，那么可以考虑对目标字符串进行单词标记。我使用nltk推荐的word_tokenize:
from nltk.tokenize import word_tokenize
下面是接受答案的标记化字符串:
a_string = "A string is more than its parts!"
tokens = word_tokenize(a_string)
tokens
Out[46]: ['A', 'string', 'is', 'more', 'than', 'its', 'parts', '!']
接受的答案修改如下:
matches_1 = ["more", "wholesome", "milk"]
[x in tokens for x in matches_1]
Out[42]: [True, False, False]
在公认的答案中，单词“more”仍然是匹配的。但是，如果“mo”成为匹配字符串，接受的答案仍然找到匹配。这是我不希望看到的行为。
matches_2 = ["mo", "wholesome", "milk"]
[x in a_string for x in matches_1]
Out[43]: [True, False, False]
使用单词标记化，“mo”不再匹配:
[x in tokens for x in matches_2]
Out[44]: [False, False, False]
这是我想要的附加行为。这个答案也回答了这里的重复问题。
为了增加regex的多样性:
import re
if any(re.findall(r'a|b|c', str, re.IGNORECASE)):
print 'possible matches thanks to regex'
else:
print 'no matches'
或者如果你的列表太长- any(re.findall(r'|'.join(a)， str, re.IGNORECASE))
data = "firstName and favoriteFood"
mandatory_fields = ['firstName', 'lastName', 'age']
# for each
for field in mandatory_fields:
if field not in data:
print("Error, missing req field {0}".format(field));
# still fine, multiple if statements
if ('firstName' not in data or
'lastName' not in data or
'age' not in data):
print("Error, missing a req field");
# not very readable, list comprehension
missing_fields = [x for x in mandatory_fields if x not in data]
if (len(missing_fields)>0):
print("Error, missing fields {0}".format(", ".join(missing_fields)));
