"Paul McGuire" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > <[EMAIL PROTECTED]> wrote in message > news:[EMAIL PROTECTED] > > Problem: > > > > You have a list of unknown length, such as this: list = > > [X,X,X,O,O,O,O]. You want to extract all and only the X's. You know > > the X's are all up front and you know that the item after the last X is > > an O, or that the list ends with an X. There are never O's between > > X's. > > > > I have been using something like this: > > _____________________ > > > > while list[0] != O: > > storage.append(list[0]) > > list.pop(0) > > if len(list) == 0: > > break > > _____________________ > > > > But this seems ugly to me, and using "while" give me the heebies. Is > > there a better approach? > > > > hope this is clear. > > thanks > > > Use itertools. > > >>> import itertools > >>> lst = "X,X,X,O,O,O,O,O,X,X,X,X,O,X".split(",") > >>> [z for z in itertools.takewhile(lambda x:x=="X",lst)] > ['X', 'X', 'X'] > > > -- Paul >
duh, last line should be: >>> list(itertools.takewhile(lambda x:x=="X",lst)) ['X', 'X', 'X'] (Also, don't name variables "list") -- Paul -- http://mail.python.org/mailman/listinfo/python-list
