nikhil Pandey wrote:
> hi,
> I want to iterate over the lines of a file and when i find certain lines,
> i need another loop starting from the next of that "CERTAIN" line till a
> few (say 20) lines later. so, basically i need two pointers to lines (one
> for outer loop(for each line in file)) and one for inner loop. How can i
> do that in python? please help. I am stuck up on this.
Here's an example that prints the three lines following a line containing a
'*':
Example data:
$ cat tmp.txt
alpha
*beta
*gamma
delta
epsilon
zeta
*eta
The python script:
$ cat tmp.py
from itertools import islice, tee
with open("tmp.txt") as f:
while True:
for outer in f:
print outer,
if "*" in outer:
f, g = tee(f)
for inner in islice(g, 3):
print " ", inner,
break
else:
break
The script's output:
$ python tmp.py
alpha
*beta
*gamma
delta
epsilon
*gamma
delta
epsilon
zeta
delta
epsilon
zeta
*eta
$
As you can see the general logic is relatively complex; it is likely that we
can come up with a simpler solution if you describe your actual requirement
in more detail.
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