Python Lambda if statements

Question

I'm trying to make a list of the number of days corresponding to months and I need to account for leap years and I want to be able to access either 28 days or 29 days depending on if it's a leap year. This is what I have:

def code(x)
    monthdays = [31, lambda x: 28 if leapyear(x) == False else 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
    return months[1]

leapyear() is just a function with 1 parameter that returns True if it is a leapyear and False otherwise. For some reason that won't return the number I want. How else can I do this?

Perhaps, it set's x to 28 when there is no leap year (from what I am getting). — Zizouz212
– Zizouz212, Commented Apr 15, 2015 at 1:41

Óscar López · Accepted Answer · 2015-04-15 01:48:46Z

3

You don't need a lambda here (and anyway you're not calling it), a simple conditional expression will do the trick. Try this:

monthdays = [31, 29 if leapyear(x) else 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

Also, I believe that in the last line you meant this:

return monthdays[1]

…Otherwise what's the point of creating monthdays if we're not going to use it? Even more, why create a whole list if we're interested in a single position?

edited Apr 15, 2015 at 1:48

answered Apr 15, 2015 at 1:43

Óscar López

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1 Comment

flarp Over a year ago

Thanks! and sorry, I was in kind of a rush when I asked my question and didn't pay attention to my variable name. Thanks!

koukouviou · Accepted Answer · 2015-04-15 01:50:06Z

0

If you want to be precise about what is a leap year and calendar events it is recommended to use calendar.monthrange. You can use it like this:

from calendar import monthrange

year = 2015
days = []
for month in range(1,13):
    days.append(monthrange(year, month)[1])

print(days)

which returns a list containing the number of days for each month of a given year:

[31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

and if you just want Feb's number of days you can just calculate that:

from calendar import monthrange

year = 2015
feb_days = monthrange(year, 2)[1]
print(feb_days)

answered Apr 15, 2015 at 1:50

koukouviou

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