On Thu, Nov 5, 2009 at 9:23 PM, Peng Yu <pengyu...@gmail.com> wrote: > On Thu, Nov 5, 2009 at 10:25 PM, Chris Rebert <c...@rebertia.com> wrote: >> On Thu, Nov 5, 2009 at 8:19 PM, Peng Yu <pengyu...@gmail.com> wrote: >>> Suppose I have a list of strings, A. I want to compute the list (call >>> it B) of strings that are elements of A but doesn't match a regex. I >>> could use a for loop to do so. In a functional language, there is way >>> to do so without using the for loop. >>> >>> I'm wondering what is the best way to compute B in python. >> >> Since this sounds rather homework-y, I'll only give you a pointer: >> http://docs.python.org/tutorial/datastructures.html#list-comprehensions > > Now, I want to in-place delete elements in A that matches the regex. I > know that I need to use del. But I'm not sure how to use the > functional style programming for this problem. Would you please let me > know?
Deletion is an imperative operation which has no direct equivalent in functional languages, so your question is nonsensical. To do it functionally, instead of deleting, you simply build a new list that omits the undesired elements. See also the built-in function filter(). Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list