How can I check for NaN values?

Question

float(\'nan\') results in Nan (not a number). But how do I check for it? Should be very easy, but I cannot find it.

Answer 1

for strings in panda take pd.isnull:

if not pd.isnull(atext):
  for word in nltk.word_tokenize(atext):

the function as feature extraction for NLTK

def act_features(atext):
features = {}
if not pd.isnull(atext):
  for word in nltk.word_tokenize(atext):
    if word not in default_stopwords:
      features['cont({})'.format(word.lower())]=True
return features