0609dev

parse: most formats to date and/or time

from dateutil.parser import parse
 ser_ts = ser.map(lambda x: parse(x))
 ser_ts.dt.dayofweek
 ser_ts.dt.weekofyear

Counter: count elements

from collections import Counter
 def frequency_dictionary(words):
   return Counter(words)

set: returns unique value of array, list

set(my_dictionary.values())

defaultdict(): used when prevent error for non-existing key

from collections import defaultdict

def count_first_letters(names):
    a = defaultdict(lambda : 0)
    for key in names.key():
        a[key[0]] = len(a[key[0]]) + len(names[key])
    return a