Check if a string in a Pandas DataFrame column is in a list of strings

Question

If I have a frame like this

frame = pd.DataFrame({\'a\' : [\'the cat is blue\', \'the sky is green\', \'the dog is black\']})

and I want to

Answer 1

After going through the comments of the accepted answer of extracting the string, this approach can also be tried.

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

Let us create our list which will have strings that needs to be matched and extracted.

mylist = ['dog', 'cat', 'fish']
pattern = '|'.join(mylist)

Now let create a function which will be responsible to find and extract the substring.

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

We will use this function with pandas.DataFrame.apply

frame['matched_str'] = frame['a'].apply(lambda x: pattern_searcher(search_str=x, search_list=pattern))

Result :

              a             matched_str
   0   the cat is blue         cat
   1  the sky is green         NA
   2  the dog is black         dog