You can use apply method of DataFrame API:
import pandas as pd
import nltk
df = pd.DataFrame({'sentences': ['This is a very good site. I will recommend it to others.', 'Can you please give me a call at 9983938428. have issues with the listings.', 'good work! keep it up']})
df['tokenized_sents'] = df.apply(lambda row: nltk.word_tokenize(row['sentences']), axis=1)
Output:
>>> df
sentences
0 This is a very good site. I will recommend it ...
1 Can you please give me a call at 9983938428. h...
2 good work! keep it up
tokenized_sents
0 [This, is, a, very, good, site, ., I, will, re...
1 [Can, you, please, give, me, a, call, at, 9983...
2 [good, work, !, keep, it, up]
For finding the length of each text try to use apply and lambda function again:
df['sents_length'] = df.apply(lambda row: len(row['tokenized_sents']), axis=1)
>>> df
sentences
0 This is a very good site. I will recommend it ...
1 Can you please give me a call at 9983938428. h...
2 good work! keep it up
tokenized_sents sents_length
0 [This, is, a, very, good, site, ., I, will, re... 14
1 [Can, you, please, give, me, a, call, at, 9983... 15
2 [good, work, !, keep, it, up] 6