r.extract_keywords_from_text (x) вернет вам None
import pandas as pd
from rake_nltk import Rake
r = Rake()
df=pd.DataFrame(data = ['machine learning and fraud detection are a must learn',
'monte carlo method is great and so is hmm,pca, svm and neural net',
'clustering and cloud',
'logistical regression and data management and fraud detection'] ,columns = ['Comments'])
def rake_implement(x,r):
r.extract_keywords_from_text(x)
return r.get_ranked_phrases()
df['new_col'] =df['Comments'].apply(lambda x: rake_implement(x,r))
print(df['new_col'])
#o/p
0 [must learn, machine learning, fraud detection]
1 [monte carlo method, neural net, svm, pca, hmm...
2 [clustering, cloud]
3 [logistical regression, fraud detection, data ...
Name: new_col, dtype: object