Using += in a loop
Carl Banks
imbosol at vt.edu
Thu Aug 8 18:02:19 EDT 2002
Bill Dandreta wrote:
> All we need now is predecessor and successor functions (like Pascal
> has). I find my self wanting to use the previous and/or next element
> in a sequence sometime when looping through.
We already have it:
Python 2.1.3 (#1, Apr 20 2002, 10:14:34)
[GCC 2.95.4 20011002 (Debian prerelease)] on linux2
Type "copyright", "credits" or "license" for more information.
>>> a = [1,2,3,4,5]
>>> for item,prev,next in zip(a,[None]+a[:-1],a[1:]+[None]):
... print "Item:",item," Previous:",prev," Next:",next
...
Item: 1 Previous: None Next: 2
Item: 2 Previous: 1 Next: 3
Item: 3 Previous: 2 Next: 4
Item: 4 Previous: 3 Next: 5
Item: 5 Previous: 4 Next: None
If you need this a lot, you can write a function to encapsulate the
zip.
--
CARL BANKS
http://www.aerojockey.com
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