How to sort strings containing numbers and letters?

Question

I have a list in the following form:

['AK 40', 'AK 35', 'AK 20', '2012',
'2011', '2010', '2009', '2009',
'2007', '2006', '2006', '2005',
'2004', '2003', '2003', '2002']

Those years all represent birthyears and groupings of ages. What I need is to sort them in the following form:

['2012', '2011', '2010', ... , '2003', '2002', 'AK 20', 'AK 35', 'AK 40']

Basically, the years should be descending, from the youngest person to the oldest. But starting from age twenty they need to be treated differently.

I already tried some lambda functions I found here on stackoverflow, but unfortunately none of them worked for me due to the fact that my list contains only strings and is not mixed with integers.

Answer 1

If your strings share the same prefix ( AK in this case), you can use the following lambda function:

sort_func = lambda e : -int(e) if e.isdigit() else int(''.join(filter(str.isdigit, e)))

sorted_list = sorted(l, key = sort_func)

Where l is your initial list, for your example, this outputs:

['2012', '2011', '2010', '2009', '2009', '2007', '2006', '2006', '2005', '2004', '2003', '2003', '2002', 'AK 20', 'AK35', 'AK 40']

The above functions sorts first by the year strings (the - in -len(e) is used to sort them in descending order), then, it sorts the age groups in ascending order by the number after the prefix AK (by filtering out anything that's not a digit from the age groups' strings).

Answer 2

seq = ['AK 40', 'AK 35', 'AK 20', '2012', '2011', '2010', '2009', '2009',
       '2007', '2006', '2006', '2005', '2004', '2003', '2003', '2002']

years = [year for year in seq if year.isdigit()]
aks = [ak for ak in seq if not ak.isdigit()]
years.sort()
aks.sort()
result = years[::-1] + aks
print(result)

Answer 3

x = ['AK 40', 'AK 35', 'AK 20', '2012', '2011', '2010', '2009', '2009', '2007', '2006', '2006', '2005', '2004', '2003', '2003', '2002']

简短将是

sorted_list = sorted(x, key = lambda e : int(e.replace('AK ', '-')), reverse=True)

Answer 4

You can use a simple sort key:

d = ['AK 40', 'AK 35', 'AK 20', '2012', '2011', '2010', '2009', '2009', '2007', '2006', '2006', '2005', '2004', '2003', '2003', '2002']
new_d = sorted(d, key=lambda x:[1, -1][x.isdigit()]*int(x.split()[-1]))

Output:

['2012', '2011', '2010', '2009', '2009', '2007', '2006', '2006', '2005', '2004', '2003', '2003', '2002', 'AK 20', 'AK 35', 'AK 40']