properly delete item during "for item in..."
mrkafk at gmail.com
Thu Jul 17 18:57:32 CEST 2008
Gary Herron wrote:
> You could remove the object from the list with
> del myList[i]
> if you knew i. HOWEVER, don't do that while looping through the list!
> Changing a list's length will interact badly with the for loop's
> indexing through the list, causing the loop to mis the element following
> the deleted item.
Jumping into a thread, I know how not to do it, but not how to do it
Iterating over a copy may _probably_ work:
>>> t=['a', 'c', 'b', 'd']
>>> for el in t[:]:
However, is it really safe? Defining safe as "works reliably in every
corner case for every indexable data type"?
Con: suppose the data structure t is really, really big. Just deleting
some items from t temporarily doubles the memory consumption.
More information about the Python-list