[EMAIL PROTECTED] wrote:
> hi
> I wish to pop/del some items out of dictionary while iterating over it.
> a = { 'a':1, 'b':2 }
> for k, v in a.iteritems():
> if v==2:
> del a[k]
>
> the output say RuntimeError: dictionary changed size during iteration
> how can i suppress this message in an actual script and still get the
> final value of the dict?
> is it something like try/except/else statment?
> try:
> for v,k in a.iteritems():
> if v==something:
> del a[k]
> except RuntimeError:
> < don't know what to do here>
> else:
> < should i include this part ? >
>
> what other ways can i do this ? thanks for any help.
If you expect to delete only a few items:
>>> a = dict(a=1, b=2, c=3, d=2)
>>> delenda = [k for k, v in a.iteritems() if v == 2]
>>> for k in delenda:
... del a[k]
...
>>> a
{'a': 1, 'c': 3}
If you expect to delete most items:
>>> a = dict(a=1, b=2, c=3, d=2)
>>> a = dict((k, v) for k, v in a.iteritems() if v != 2)
>>> a
{'a': 1, 'c': 3}
or (if rebinding a is not an option)
>>> a = dict(a=1, b=2, c=3, d=2)
>>> for k, v in a.items():
... if v == 2:
... del a[k]
...
>>> a
{'a': 1, 'c': 3}
Peter
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