Karthik Gurusamy wrote:
> On Sep 5, 11:17 am, James Stroud <[EMAIL PROTECTED]> wrote:
>>
>> for i in xrange(number_of_reads):
>> for dev in devs:
>> try:
>> _reader = getattr(dev, 'read%d' % i)
>> _reader()
>> except Exception, e:
>> print e
>> devs.remove(dev)
>
> I see in many of the solutions suggested above, the devs sequence/
> iterator is being modified while iterating. I know it is not defined
> for interation over dictionary keys. Are they defined for other
> collections like lists?
Good eye! My code is broke as you have noticed:
py> r = range(5)
py> for i in r:
... print i
... if i % 2:
... r.remove(i)
...
0
1
3
For longer sequences, the algorithm I've used in these cases in the past
goes something like this:
py> r = range(10, 17)
py> print r
[10, 11, 12, 13, 14, 15, 16]
py>
py> i = 0
py> while i < len(r):
... j = r[i]
... print j
... if j % 2:
... r.remove(j)
... else:
... i += 1
...
10
11
12
13
14
15
16
py> print r
[10, 12, 14, 16]
Which would change my problematic code above to:
for i in xrange(number_of_reads):
j = 0
while j < len(devs):
try:
_reader = getattr(devs[j], 'read%d' % i)
_reader()
j += 1
except Exception, e:
print e
devs.remove(dev)
Another way is to make a copy of devs, if devs is short, which makes my
problematic code into a matter of a "typo"--maybe I can make this claim
to save some face?
for i in xrange(number_of_reads):
for dev in devs[:]:
try:
_reader = getattr(dev, 'read%d' % i)
_reader()
except Exception, e:
print e
devs.remove(dev)
James
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095
http://www.jamesstroud.com/
--
http://mail.python.org/mailman/listinfo/python-list
