Python: sort list except first line

Question

I have this list :

[['Nom', 'Francais', 'Anglais', 'Maths'], ['Catherine', '9', '17', '9'], ['Karim', '12', '15', '11'], ['Rachel', '15', '15', '14'], ['Roger', '12', '14', '12'], ['Gabriel', '7', '13', '8'], ['Francois', '14', '8', '15'], ['Henri', '10', '12', '13'], ['Stephane', '18', '12', '8'], ['Karine', '9', '10', '10'], ['Marie', '10', '10', '10'], ['Claire', '15', '9', '12'], ['Marine', '12', '9', '12']]

I want to sort it with the names (or, in another words, by alphabetical order of the [0] element of each list within the list) but i don't want don't want the first list (['Nom', 'Francais', 'Anglais', 'Maths']) to be sorted with the others , how can in do that ?

Thanks a lot !

Answer 1

You can use range assignment:

>>> from pprint import pprint # just to have a nice display
>>> data = [['Nom', 'Francais', 'Anglais', 'Maths'], ['Catherine', '9', '17', '9'], ['Karim', '12', '15', '11'], ['Rachel', '15', '15', '14'], ['Roger', '12', '14', '12'], ['Gabriel', '7', '13', '8'], ['Francois', '14', '8', '15'], ['Henri', '10', '12', '13'], ['Stephane', '18', '12', '8'], ['Karine', '9', '10', '10'], ['Marie', '10', '10', '10'], ['Claire', '15', '9', '12'], ['Marine', '12', '9', '12']]
>>> pprint(data)
[['Nom', 'Francais', 'Anglais', 'Maths'],
 ['Catherine', '9', '17', '9'],
 ['Karim', '12', '15', '11'],
 ['Rachel', '15', '15', '14'],
 ['Roger', '12', '14', '12'],
 ['Gabriel', '7', '13', '8'],
 ['Francois', '14', '8', '15'],
 ['Henri', '10', '12', '13'],
 ['Stephane', '18', '12', '8'],
 ['Karine', '9', '10', '10'],
 ['Marie', '10', '10', '10'],
 ['Claire', '15', '9', '12'],
 ['Marine', '12', '9', '12']]
>>> data[1:] = sorted(data[1:])
>>> pprint(data)
[['Nom', 'Francais', 'Anglais', 'Maths'],
 ['Catherine', '9', '17', '9'],
 ['Claire', '15', '9', '12'],
 ['Francois', '14', '8', '15'],
 ['Gabriel', '7', '13', '8'],
 ['Henri', '10', '12', '13'],
 ['Karim', '12', '15', '11'],
 ['Karine', '9', '10', '10'],
 ['Marie', '10', '10', '10'],
 ['Marine', '12', '9', '12'],
 ['Rachel', '15', '15', '14'],
 ['Roger', '12', '14', '12'],
 ['Stephane', '18', '12', '8']]

Answer 2

Personally, I'd do something like this. But it assumes you're semi-comfortable with Pandas. This gives you a lot more flexibility to do more with the data.

import pandas as pd

nl = [['Nom', 'Francais', 'Anglais', 'Maths'], ['Catherine', '9', '17', '9'], ['Karim', '12', '15', '11'], ['Rachel', '15', '15', '14'], ['Roger', '12', '14', '12'], ['Gabriel', '7', '13', '8'], ['Francois', '14', '8', '15'], ['Henri', '10', '12', '13'], ['Stephane', '18', '12', '8'], ['Karine', '9', '10', '10'], ['Marie', '10', '10', '10'], ['Claire', '15', '9', '12'], ['Marine', '12', '9', '12']]

df = pd.DataFrame(columns = nl[0])

for l, c in zip(nl[0], range(4)):
    df[l] = [ r[c] for r in nl[1:] ]

df.sort_values(by = 'Nom', inplace = True)
df.reset_index(drop = True, inplace = True)

which yields:

          Nom Francais Anglais Maths
0   Catherine        9      17     9
1      Claire       15       9    12
2    Francois       14       8    15
3     Gabriel        7      13     8
4       Henri       10      12    13
5       Karim       12      15    11
6      Karine        9      10    10
7       Marie       10      10    10
8      Marine       12       9    12
9      Rachel       15      15    14
10      Roger       12      14    12
11   Stephane       18      12     8

and then if you need a .csv per your most recent comment, it's simply:

df.to_csv('/directory/my_filename.csv', index = False)