![](/img/trans.png)
[英]How to check if string in list of strings is in pandas dataframe column
[英]Check if a string in a Pandas DataFrame column is in a list of strings
如果我有这样的框架
frame = pd.DataFrame({'a' : ['the cat is blue', 'the sky is green', 'the dog is black']})
我想检查这些行中是否有任何一行包含某个单词,我只需要这样做。
frame['b'] = frame.a.str.contains("dog") | frame.a.str.contains("cat") | frame.a.str.contains("fish")
frame['b']
输出:
True
False
True
如果我决定列一个清单
mylist =['dog', 'cat', 'fish']
我将如何检查行中是否包含列表中的某个单词?
frame = pd.DataFrame({'a' : ['the cat is blue', 'the sky is green', 'the dog is black']})
frame
a
0 the cat is blue
1 the sky is green
2 the dog is black
str.contains
方法接受一个正则表达式模式:
mylist = ['dog', 'cat', 'fish']
pattern = '|'.join(mylist)
pattern
'dog|cat|fish'
frame.a.str.contains(pattern)
0 True
1 False
2 True
Name: a, dtype: bool
由于支持正则表达式模式,您还可以嵌入标志:
frame = pd.DataFrame({'a' : ['Cat Mr. Nibbles is blue', 'the sky is green', 'the dog is black']})
frame
a
0 Cat Mr. Nibbles is blue
1 the sky is green
2 the dog is black
pattern = '|'.join([f'(?i){animal}' for animal in mylist]) # python 3.6+
pattern
'(?i)dog|(?i)cat|(?i)fish'
frame.a.str.contains(pattern)
0 True # Because of the (?i) flag, 'Cat' is also matched to 'cat'
1 False
2 True
对于列表应该工作
print frame[frame['a'].isin(mylist)]
http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.isin.html
在浏览了提取字符串的已接受答案的注释后,也可以尝试这种方法。
frame = pd.DataFrame({'a' : ['the cat is blue', 'the sky is green', 'the dog is black']})
frame
a
0 the cat is blue
1 the sky is green
2 the dog is black
让我们创建我们的列表,其中包含需要匹配和提取的字符串。
mylist = ['dog', 'cat', 'fish']
pattern = '|'.join(mylist)
现在让我们创建一个函数来负责查找和提取子字符串。
import re
def pattern_searcher(search_str:str, search_list:str):
search_obj = re.search(search_list, search_str)
if search_obj :
return_str = search_str[search_obj.start(): search_obj.end()]
else:
return_str = 'NA'
return return_str
我们将这个函数与 pandas.DataFrame.apply 一起使用
frame['matched_str'] = frame['a'].apply(lambda x: pattern_searcher(search_str=x, search_list=pattern))
结果 :
a matched_str
0 the cat is blue cat
1 the sky is green NA
2 the dog is black dog
例如,我们可以使用管道同时检查三种模式
for i in range(len(df)):
if re.findall(r'car|oxide|gen', df.iat[i,1]):
df.iat[i,2]='Yes'
else:
df.iat[i,2]='No'
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.