dataframe['column_name']=dataframe['column_name'].apply(str)
import re
import nltk
from nltk.tokenize import word_tokenize
nltk.download('punkt')
sentences = word_tokenize("I love to learn NLP
'a :(")
#for i in range(len(sentences)):
sentences = [word.lower() for word in sentences if re.match('^[a-zA-Z]+', word)]
sentences
letters_only = re.sub("[^a-zA-Z]", # Search for all non-letters
" ", # Replace all non-letters with spaces
str(location))