Creating slice notation from string
python at mrabarnett.plus.com
Thu Sep 3 00:11:17 CEST 2009
> I'm trying to NOT create a parser to do this .... and I'm sure that
> it's easy if I could only see the light!
> Is it possible to take an arbitrary string in the form "1:2", "1",
> ":-1", etc. and feed it to slice() and then apply the result to an
> existing list?
> For example, I have a normal python list. Let's say that x = [1,2,3,4]
> and I have a string, call it "s', in the format "[2:3]". All I need to
> do is to apply "s" to "x" just like python would do.
> I can, of course, convert "x" to a list with split(), convert the 2
> and 3 to ints, and then do something like: x[a:b] ... but I'd like
> something more general. I think the answer is in slice() but I'm lost.
>>> x = [1,2,3,4]
>>> s = "[2:3]"
>>> # Using map.
>>> x[slice(*map(int, s.strip("").split(":")))]
>>> # Using a list comprehension.
>>> x[slice(*[int(i) for i in s.strip("").split(":")])]
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