Wrapping around a list in Python.
shengjie.shengjie at live.com
shengjie.shengjie at live.com
Mon Dec 16 00:26:49 EST 2013
On Monday, 16 December 2013 13:10:22 UTC+8, Gary Herron wrote:
> On 12/15/2013 08:38 PM, shengjie.shengjie at live.com wrote:
>
> > Hi guys, I am trying to create a fixed list which would allow my values to be wrapped around it.
>
> > For example i have 10 values : 0,1,2,3,4,5,6,7,8,9
>
> > I need to create a list which contains 4 numbers and when the number exceeds the list, it would overwrite the first value.
>
> > [0,1,2,3]
>
> > [4,1,2,3]
>
> > [5,4,1,2]
>
> >
>
> > Thanks in advance and much help appreciated.
>
>
>
> Is the output really three lists as you show. Or is that one list whose
>
> contents you have shown three snapshots of? Then what was the point of
>
> putting 4 in the first spot when you are just going to move it to the
>
> second spot? And why stop at 4 and 5? What about 7, 8, and 9?
>
>
>
> Are you really shifting elements onto the beginning of the list and off
>
> the end of the list? (That's easy to do, but is that what you want?)
>
>
>
> If I follow your example a few elements further I get [9,8,7,6], just
>
> the last four elements of the original list in reverse order -- so there
>
> is no need fill a list and "wrap-around" -- just grab the last four
>
> elements and reverse them.
>
>
>
> Or have I misunderstood the problem completely? (I think that's
>
> likely.) I'm sure Python is general enough to do what you want, but
>
> you'll have to do a much better job telling is what you want. While you
>
> are at it, tell us what you've already done, and how it fails to do
>
> whatever it is you want.
>
>
>
> Gary Herron
The idea is to grab the last 4 elements of the array. However i have an array that contains a few hundred elements in it. And the values continues to .append over time. How would i be able to display the last 4 elements of the array under such a condition?
More information about the Python-list
mailing list