If you wants to just sort your list then use sorted function and pass key
value = a function that converts date-string into Python's datetime
object as lambda d: datetime.strptime(d, '%m/%Y')
, check following code example for your list as L
:
>>> from datetime import datetime
>>> sorted(L, key = lambda d: datetime.strptime(d, '%m/%Y'))
['1/2013', '2/2013', '3/2013', '7/2013', '10/2013',
'11/2013', '12/2013', '1/2014', '2/2014', '4/2014'] # indented by hand
To split "list of month/year strings" into "list of list of consecutive months", you can use following script (read comments), In which, first I sorted the list L
then groups strings on the basis of consecutive month (to check consecutive month I written a function):
def is_cm(d1, d2):
""" is consecutive month pair?
: Assumption d1 is older day's date than d2
"""
d1 = datetime.strptime(d1, '%m/%Y')
d2 = datetime.strptime(d2, '%m/%Y')
y1, y2 = d1.year, d2.year
m1, m2 = d1.month, d2.month
if y1 == y2: # if years are same d2 should be in next month
return (m2 - m1) == 1
elif (y2 - y1) == 1: # if years are consecutive
return (m1 == 12 and m2 == 1)
It works as follows:
>>> is_cm('1/2012', '2/2012')
True # yes, consecutive
>>> is_cm('12/2012', '1/2013')
True # yes, consecutive
>>> is_cm('1/2015', '12/2012') # None --> # not consecutive
>>> is_cm('12/2012', '2/2013')
False # not consecutive
Code to split your code:
def result(dl):
"""
dl: dates list - a iterator of 'month/year' strings
type: list of strings
returns: list of lists of strings
"""
#Sort list:
s_dl = sorted(dl, key=lambda d: datetime.strptime(d, '%m/%Y'))
r_dl = [] # list to be return
# split list into list of lists
t_dl = [s_dl[0]] # temp list
for d in s_dl[1:]:
if not is_cm(t_dl[-1], d): # check if months are not consecutive
r_dl.append(t_dl)
t_dl = [d]
else:
t_dl.append(d)
return r_dl
result(L)
Don't forget to include from datetime import datetime
, This trick I believe you can easily update for a new list of dates in which dates are in other format.
After @9000 hint I could simplified my sorted function and removed old answer if you wants to check old script check @codepad.