Looking at the next element in a for loop

[-]

Hi,

If I have a simple for loop like this:

for a in b:
print a

Is there a way I can get the next element in the loop? Something like this:

for a in b:
if a == 1:
print <next a>

[Tor Iver Wilhelmsen]

ma***********@hotmail.com (-) writes:

Is there a way I can get the next element in the loop? Something like this:

for a in b:
if a == 1:
print <next a>

No, not as long as you use an iterator. If you use an index instead,
it's easy of course.

for i in xrange(len(b)):
if b[i] is 1:
print b[i+1]

[Peter Otten]

- wrote:

If I have a simple for loop like this:

for a in b:
print a

Is there a way I can get the next element in the loop? Something like
this:

for a in b:
if a == 1:
print <next a>

You could reverse the logic:

wasMatch = False
for a in [1,2,1,1,1,3,1,4]: .... if wasMatch: print a,
.... wasMatch = a == 1
....
2 1 1 3 4
Or do something like this:
b = [1,2,1,1,1,3,1,4]
for a, nexta in zip(b, b[1:]): .... if a == 1: print nexta,
....
2 1 1 3 4

If you like the latter, you can use the window() function on the itertools
example page http://www.python.org/doc/current/li...s-example.html
for a better implementation:

for a, nexta in window(b):
if a == 1: print nexta,

Peter