[python] month name to month number and vice versa in python

I am trying to create a function that can convert a month number to an abbreviated month name or an abbreviated month name to a month number. I thought this might be a common question but I could not find it online.

I was thinking about the calendar module. I see that to convert from month number to abbreviated month name you can just do calendar.month_abbr[num]. I do not see a way to go the other direction though. Would creating a dictionary for converting the other direction be the best way to handle this? Or is there a better way to go from month name to month number and vice versa?

You can use below as an alternative.

1. Month to month number:

from time import strptime

strptime('Feb','%b').tm_mon

2. Month number to month:

import calendar

calendar.month_abbr[2] or calendar.month[2]

One more:

def month_converter(month):
    months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    return months.index(month) + 1

Building on ideas expressed above, This is effective for changing a month name to its appropriate month number:

from time import strptime
monthWord = 'september'

newWord = monthWord [0].upper() + monthWord [1:3].lower() 
# converted to "Sep"

print(strptime(newWord,'%b').tm_mon) 
# "Sep" converted to "9" by strptime

To get the full calendar name from the month number, you can use calendar.month_name. Please see the documentation for more details: https://docs.python.org/2/library/calendar.html

month_no = 1
month = calendar.month_name[month_no]

# month provides "January":
print(month)

Here's yet another way to do it.

monthToNum(shortMonth):

    return {
            'jan' : 1,
            'feb' : 2,
            'mar' : 3,
            'apr' : 4,
            'may' : 5,
            'jun' : 6,
            'jul' : 7,
            'aug' : 8,
            'sep' : 9, 
            'oct' : 10,
            'nov' : 11,
            'dec' : 12
    }[shortMonth]

Using calendar module:

Number-to-Abbr calendar.month_abbr[month_number]

Abbr-to-Number list(calendar.month_abbr).index(month_abbr)

Here is a more comprehensive method that can also accept full month names

def month_string_to_number(string):
    m = {
        'jan': 1,
        'feb': 2,
        'mar': 3,
        'apr':4,
         'may':5,
         'jun':6,
         'jul':7,
         'aug':8,
         'sep':9,
         'oct':10,
         'nov':11,
         'dec':12
        }
    s = string.strip()[:3].lower()

    try:
        out = m[s]
        return out
    except:
        raise ValueError('Not a month')

example:

>>> month_string_to_number("October")
10 
>>> month_string_to_number("oct")
10

Information source: Python Docs

To get month number from month name use datetime module

import datetime
month_number = datetime.datetime.strptime(month_name, '%b').month

# To  get month name
In [2]: datetime.datetime.strftime(datetime.datetime.now(), '%a %b %d, %Y')
Out [2]: 'Thu Aug 10, 2017'

# To get just the month name, %b gives abbrevated form, %B gives full month name
# %b => Jan
# %B => January
dateteime.datetime.strftime(datetime_object, '%b')

Just for fun:

from time import strptime

strptime('Feb','%b').tm_mon

def month_num2abbr(month):
    month = int(month)
    import calendar
    months_abbr = {month: index for index, month in enumerate(calendar.month_abbr) if month}
    for abbr, month_num in months_abbr.items():
        if month_num==month:
            return abbr
    return False

print(month_num2abbr(7))

If you don't want to import the calendar library, and need something that is a bit more robust -- you can make your code a little bit more dynamic to inconsistent text input than some of the other solutions provided. You can:

1. Create a month_to_number dictionary
2. loop through the .items() of that dictionary and check if the lowercase of a string s is in a lowercase key k.

month_to_number = {
'January' : 1,         
'February' : 2,         
'March' : 3,           
'April' : 4,              
'May' : 5, 
'June' : 6,
'July' : 7, 
'August' : 8, 
'September' : 9, 
'October' : 10, 
'November' : 11, 
'December' : 12}

s = 'jun'
[v for k, v in month_to_number.items() if s.lower() in k.lower()][0]

Out[1]: 6

Likewise, if you have a list l instead of a string, you can add another for to loop through the list. The list I have created has inconsistent values, but the output is still what would be desired for the correct month number:

l = ['January', 'february', 'mar', 'Apr', 'MAY', 'JUne', 'july']
[v for k, v in month_to_number.items() for m in l if m.lower() in k.lower()]

Out[2]: [1, 2, 3, 4, 5, 6, 7]

The use case for me here is that I am using Selenium to scrape data from a website by automatically selecting a dropdown value based off of some conditions. Anyway, this requires me relying on some data that I believe our vendor is manually entering to title each month, and I don't want to come back to my code if they format something slightly differently than they have done historically.

form month name to number
d=['JAN','FEB','MAR','April','MAY','JUN','JUL','AUG','SEP','OCT','NOV','DEC']
N=input()
for i in range(len(d)):
    if d[i] == N:
        month=(i+1)
print(month)