case-insensitive list sorting, without lowercasing the result?

问题

I have a list of strings like this:

[\'Aden\', \'abel\']

I want to sort the items, case-insensitive. So I want to get:

[\'abel\', \'Aden\']

But I get the opposite with sorted() or list.sort(), because uppercase appears before lowercase.

How can I ignore the case? I\'ve seen solutions which involves lowercasing all list items, but I don\'t want to change the case of the list items.

回答1:

In Python 3.3+ there is the str.casefold method that's specifically designed for caseless matching:

sorted_list = sorted(unsorted_list, key=str.casefold)

In Python 2 use lower():

sorted_list = sorted(unsorted_list, key=lambda s: s.lower())

It works for both normal and unicode strings, since they both have a lower method.

In Python 2 it works for a mix of normal and unicode strings, since values of the two types can be compared with each other. Python 3 doesn't work like that, though: you can't compare a byte string and a unicode string, so in Python 3 you should do the sane thing and only sort lists of one type of string.

>>> lst = ['Aden', u'abe1']
>>> sorted(lst)
['Aden', u'abe1']
>>> sorted(lst, key=lambda s: s.lower())
[u'abe1', 'Aden']

回答2:

>>> x = ['Aden', 'abel']
>>> sorted(x, key=str.lower) # Or unicode.lower if all items are unicode
['abel', 'Aden']

In Python 3 str is unicode but in Python 2 you can use this more general approach which works for both str and unicode:

>>> sorted(x, key=lambda s: s.lower())
['abel', 'Aden']

回答3:

You can also try this:

>>> x = ['Aden', 'abel']
>>> x.sort(key=lambda y: y.lower())
>>> x
['abel', 'Aden']

回答4:

In python3 you can use

list1.sort(key=lambda x: x.lower()) #Case In-sensitive             
list1.sort() #Case Sensitive

回答5:

This works in Python 3 and does not involves lowercasing the result (!).

values.sort(key=str.lower)

回答6:

I did it this way for Python 3.3:

 def sortCaseIns(lst):
    lst2 = [[x for x in range(0, 2)] for y in range(0, len(lst))]
    for i in range(0, len(lst)):
        lst2[i][0] = lst[i].lower()
        lst2[i][1] = lst[i]
    lst2.sort()
    for i in range(0, len(lst)):
        lst[i] = lst2[i][1]

Then you just can call this function:

sortCaseIns(yourListToSort)

回答7:

Try this

def cSort(inlist, minisort=True):
    sortlist = []
    newlist = []
    sortdict = {}
    for entry in inlist:
        try:
            lentry = entry.lower()
        except AttributeError:
            sortlist.append(lentry)
        else:
            try:
                sortdict[lentry].append(entry)
            except KeyError:
                sortdict[lentry] = [entry]
                sortlist.append(lentry)

    sortlist.sort()
    for entry in sortlist:
        try:
            thislist = sortdict[entry]
            if minisort: thislist.sort()
            newlist = newlist + thislist
        except KeyError:
            newlist.append(entry)
    return newlist