How to sort list of String without considering Special characters and with case insensitive

Prasad, Ramit ramit.prasad at jpmorgan.com
Tue Nov 27 19:21:03 CET 2012


san wrote:
> 
> Please let me know how to sort the list of String in either ascending / descending order without considering
> special characters and case.
> ex: list1=['test1_two','testOne','testTwo','test_one']
> Applying the list.sort /sorted method results in sorted list ['test1_two', 'testOne', 'testTwo', 'test_one']
> but the without considering the special characters and case it should be
> ['testOne','test_one', 'test1_two','testTwo'] OR ['test_one','testOne','testTwo', 'test1_two' ]
> 
> list.sort /sorted method sorts based on the ascii value of the characters but Please let me knwo how do i
> achieve my expected one

You can pass a key function into list.sort() and sorted(). This
allows you to customize the sorting. In the below examples
I use lambda but you can use a non-lambda function (if you need
more complexity).

Case insensitive searches are often done by converting the 
strings being compared into the same case. Here I turned
them all uppercase.

lst = ['test1_two', 'testOne', 'testTwo', 'test_one']
lst.sort(key=lambda x: x.upper())

This will filter non-alphanumeric characters. You may
be able to create and use a translation table instead.

lst.sort( key=lambda x: ''.join( c.upper() for c in x if c 
in string.letters+string.digits ) )


~Ramit



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