Remove nan from a numpy array :

a = a[~numpy.isnan(a)]

Replace nan in a list with a number:

import math
list_name = [999 if math.isnan(x) else x for x in list_name]

Python remove whitespace in a string :

If you want to remove leading and ending spaces, use str.strip():

sentence = ' hello  apple'
sentence.strip()

If you want to remove all spaces, use str.replace():

sentence = ' hello  apple'
sentence.replace(" ", "")

If you want to remove duplicated spaces, use str.split() :

sentence = ' hello  apple'
" ".join(sentence.split())