The Python Oracle

Python data structure sort list alphabetically

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Chapters
00:00 Question
00:38 Accepted answer (Score 316)
02:11 Answer 2 (Score 40)
03:15 Answer 3 (Score 17)
03:30 Answer 4 (Score 11)
03:44 Thank you

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Full question
https://stackoverflow.com/questions/1403...

Accepted answer links:
[list]: http://docs.python.org/3/tutorial/introd...
[tuple]: http://docs.python.org/3/tutorial/datast...
[dictionary]: http://docs.python.org/3/tutorial/datast...
[official Python tutorial]: http://docs.python.org/3/tutorial/index....

Answer 2 links:
[sorted]: http://docs.python.org/2/library/functio...
[sort]: http://docs.python.org/2/library/stdtype...

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Tags
#python #list #sorting #alphabetical

#avk47



ACCEPTED ANSWER

Score 329


[] denotes a list, () denotes a tuple and {} denotes a dictionary. You should take a look at the official Python tutorial as these are the very basics of programming in Python.

What you have is a list of strings. You can sort it like this:

In [1]: lst = ['Stem', 'constitute', 'Sedge', 'Eflux', 'Whim', 'Intrigue']

In [2]: sorted(lst)
Out[2]: ['Eflux', 'Intrigue', 'Sedge', 'Stem', 'Whim', 'constitute']

As you can see, words that start with an uppercase letter get preference over those starting with a lowercase letter. If you want to sort them independently, do this:

In [4]: sorted(lst, key=str.lower)
Out[4]: ['constitute', 'Eflux', 'Intrigue', 'Sedge', 'Stem', 'Whim']

You can also sort the list in reverse order by doing this:

In [12]: sorted(lst, reverse=True)
Out[12]: ['constitute', 'Whim', 'Stem', 'Sedge', 'Intrigue', 'Eflux']

In [13]: sorted(lst, key=str.lower, reverse=True)
Out[13]: ['Whim', 'Stem', 'Sedge', 'Intrigue', 'Eflux', 'constitute']

Please note: If you work with Python 3, then str is the correct data type for every string that contains human-readable text. However, if you still need to work with Python 2, then you might deal with unicode strings which have the data type unicode in Python 2, and not str. In such a case, if you have a list of unicode strings, you must write key=unicode.lower instead of key=str.lower.




ANSWER 2

Score 44


Python has a built-in function called sorted, which will give you a sorted list from any iterable you feed it (such as a list ([1,2,3]); a dict ({1:2,3:4}), although it will just return a sorted list of the keys; a set ({1,2,3,4); or a tuple ((1,2,3,4))).

>>> x = [3,2,1]
>>> sorted(x)
[1, 2, 3]
>>> x
[3, 2, 1]

Lists also have a sort method that will perform the sort in-place (x.sort() returns None but changes the x object) .

>>> x = [3,2,1]
>>> x.sort()
>>> x
[1, 2, 3]

Both also take a key argument, which should be a callable (function/lambda) you can use to change what to sort by.
For example, to get a list of (key,value)-pairs from a dict which is sorted by value you can use the following code:

>>> x = {3:2,2:1,1:5}
>>> sorted(x.items(), key=lambda kv: kv[1])  # Items returns a list of `(key,value)`-pairs
[(2, 1), (3, 2), (1, 5)]



ANSWER 3

Score 18


You're dealing with a python list, and sorting it is as easy as doing this.

my_list = ['Stem', 'constitute', 'Sedge', 'Eflux', 'Whim', 'Intrigue']
my_list.sort()



ANSWER 4

Score 11


You can use built-in sorted function.

print sorted(['Stem', 'constitute', 'Sedge', 'Eflux', 'Whim', 'Intrigue'])