CODEWITHSUNDEEP
pythonlistsorting
user2696287
user2696287

Reputation: 335

alphabetical tie-breakers in lists python

I have a list that looks like this:

['Ivan Connolly,50', 'Claudia Zingaro,50', 'Jeffie Honaker,50', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,48', 'Cristi Authement,47', 'Yadira Millwood,47', 'Invalid Name,46']

The numbers represent student test scores. I want to use the sorted() function to sort the list out in student ranking, and tie breakers are names in alphabetical order. I am not too familiar with this function, so your help would be greatly appreciated! =)

Upvotes: 0

Views: 520

Answers (3)

Jon Clements
Jon Clements

Reputation: 142206

Starting with:

L = ['Ivan Connolly,50', 'Claudia Zingaro,50', 'Jeffie Honaker,50', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,48', 'Cristi Authement,47', 'Yadira Millwood,47', 'Invalid Name,46']

To sort by multiple keys, first, sort on the "secondary" key in the order you wish it to be, eg, we'll put it in alphabetical order ignoring case:

L.sort(key=str.lower)

Gives us:

['Claudia Zingaro,50', 'Cristi Authement,47', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,46', 'Invalid Name,48', 'Ivan Connolly,50', 'Jeffie Honaker,50', 'Yadira Millwood,47']

Then, we sort in descending order the score field:

L.sort(key=lambda L: int(L.rpartition(',')[2]), reverse=True)

That gives L a final result of:

['Claudia Zingaro,50', 'Ivan Connolly,50', 'Jeffie Honaker,50', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,48', 'Cristi Authement,47', 'Yadira Millwood,47', 'Invalid Name,46']

Upvotes: 0

TerryA
TerryA

Reputation: 60004

Use the key parameter with sorted(), and adding your own function.

>>> L = ['Ivan Connolly,50', 'Claudia Zingaro,50', 'Jeffie Honaker,50', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,48', 'Cristi Authement,47', 'Yadira Millwood,47', 'Invalid Name,46']
>>> def mysort(x):
...     temp = x.split(',')
...     return (-int(temp[1]), temp[0])
... 
>>> sorted(L, key=mysort)
['Claudia Zingaro,50', 'Ivan Connolly,50', 'Jeffie Honaker,50', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,48', 'Cristi Authement,47', 'Yadira Millwood,47', 'Invalid Name,46']

The function is called with each value in the list. The function will return something like [46, 'Invalid Name']. Then, sorted() sees this and sorts it based on the list given, the first item having more priority.

Upvotes: 1

user2110286
user2110286

Reputation:

You can use sort(key=...) function.

Try this:

L = ['Ivan Connolly,50', 'Claudia Zingaro,50', 'Jeffie Honaker,50', 'Floria Rozar,49', 'Hyun Castleberry,48', 'Invalid Name,48', 'Cristi Authement,47', 'Yadira Millwood,47', 'Invalid Name,46']
L.sort(key=lambda x:int(x.split(',')[1]))

Output:

['Invalid Name,46', 'Cristi Authement,47', 'Yadira Millwood,47', 'Hyun Castleberry,48', 'Invalid Name,48', 'Floria Rozar,49', 'Ivan Connolly,50', 'Claudia Zingaro,50', 'Jeffie Honaker,50']

It is simple and clear.

Upvotes: 1

Related Questions