Which implementation of current_quarter function would be more pythonic?

Question

Which implementation of current_quarter function would be more pythonic, and why?

First version seems to be easier to extend. However, it's a kind of function you would not extend because the notion of a quarter wouldn't change.

In the second version it is easier to grasp the mechanics.

def current_quarter(input_date):
    months_baskets = [(1,2,3), (4,5,6), (7,8,9), (10,11,12)]
    quarters = (1,2,3,4)
    for idx, basket in enumerate(months_baskets):
        if input_date.month in basket:
            return quarters[idx]
            break

def current_quarter(input_date):
    if input_date.month in (1, 2, 3):
        return 1
    elif input_date.month in (4, 5, 6):
        return 2
    elif input_date.month in (7, 8, 9):
        return 3
    elif input_date.month in (10, 11, 12):
        return 4

Since it's about working code, this question would be better suited for [codereview.stackexchange.com](http://codereview.stackexchange.com). — Lukas Graf, Oct 25 '14 at 21:31
You might do something like `(input_date.month-1)//3` . Check out this post: http://stackoverflow.com/questions/1406131/is-there-a-python-function-to-determine-which-quarter-of-the-year-a-date-is-in — Alex Woolford, Oct 25 '14 at 21:33
@AlexWoolford: this is indeed a duplicate, thanks for pointing that out. — Martijn Pieters, Oct 25 '14 at 21:42

Martijn Pieters · Answer 1 · 2014-10-25T21:39:10.713

3

Neither is; it is much simpler to compute the quarter mathematically:

def current_quarter(input_date):
    return (input_date.month - 1) // 3 + 1

Quick demo:

>>> for month in range(1, 13):
...     quarter = (month - 1) // 3 + 1
...     print 'Month: {0:02d}, Quarter: {1:d}'.format(month, quarter)
... 
Month: 01, Quarter: 1
Month: 02, Quarter: 1
Month: 03, Quarter: 1
Month: 04, Quarter: 2
Month: 05, Quarter: 2
Month: 06, Quarter: 2
Month: 07, Quarter: 3
Month: 08, Quarter: 3
Month: 09, Quarter: 3
Month: 10, Quarter: 4
Month: 11, Quarter: 4
Month: 12, Quarter: 4

edited Oct 25 '14 at 21:39

answered Oct 25 '14 at 21:32

Martijn Pieters

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lots of edits there ;) – Padraic Cunningham Oct 25 '14 at 21:33
usually alcohol related on saturday nights :) – Padraic Cunningham Oct 25 '14 at 21:36
do you not have to do the -1 before the division? – Padraic Cunningham Oct 25 '14 at 21:39
@PadraicCunningham: I do, yes.. – Martijn Pieters Oct 25 '14 at 21:39

score 1 · Accepted Answer · edited Oct 25 '14 at 22:03

1

I am not sure if I got what Martjin is trying to propose, so I would take this liberty to propose my solution

>>> def current_quarter(input_date):
        return (input_date.month - 1) // 3 + 1
>>>
>>> from datetime import datetime
>>> [(m, current_quarter(datetime(2014, m, 1))) for m in range(1,13)]
[(1, 1), (2, 1), (3, 1), (4, 2), (5, 2), (6, 2), (7, 3), (8, 3), (9, 3), (10, 4), (11, 4), (12, 4)]

edited Oct 25 '14 at 22:03

Lukas Graf

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answered Oct 25 '14 at 21:40

Abhijit

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1

`input_date` is a date object, not an integer. – Martijn Pieters Oct 25 '14 at 21:41
1

Ok, I'm confused here - this is basically @MartijnPieter's answer copied over, and "demonstrated" by code that doesn't match what the function expects? – Lukas Graf Oct 25 '14 at 21:54
@LukasGraf: Not exactly. Check his edit :-). I just realized he edited his question and it matches mine. But its now too late as this is an accepted answer – Abhijit Oct 25 '14 at 21:56
I see. The demo code is still wrong though (and the indentation of the function body). – Lukas Graf Oct 25 '14 at 21:59
@LukasGraf: Code copied from Idle, and I believe people understand's that. Regarding the example code, I was bit lazy, but now its fixed. – Abhijit Oct 25 '14 at 22:01

Which implementation of current_quarter function would be more pythonic?

2 Answers2