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POHow to delete list elements while cycling the list itself without duplicate it
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copied!<p>I lost a little bit of time in this Python for statement:</p> <pre><code>class MyListContainer: def __init__(self): self.list = [] def purge(self): for object in self.list: if (object.my_cond()): self.list.remove(object) return self.list container = MyListContainer() # now suppose both obj.my_cond() return True obj1 = MyCustomObject(par) obj2 = MyCustomObject(other_par) container.list = [obj1, obj2] # returning not an empty list but [obj2] container.purge() </code></pre> <p>It doesn't work as I expected because when the cycle in "purge" delete the first object in list the second one is shifted to the beginning of the list and the cycle is ended.</p> <p>I solved duplicating self.list before the for cycle:</p> <pre><code>... local_list = self.list[:] for object in local_list: ... </code></pre> <p>I suppose that the for statement stop working because I'm changing the length of the original list. Can someone clarify this point ? </p> <p>And is there a more "elegant" way to solve this problem ? If I have more than few elements inside the list, duplicating it every time does not seem a good idea.</p> <p>Maybe the filter() function is the right one but i whish to have some other approach if any. </p> <p>I'm a newbie.</p> <hr> <p>To summarize your useful answers:</p> <ul> <li>Never edit a list you are looping</li> <li>Duplicate the list or use list comprehensions</li> <li>Duplicating a list could not waste your memory or in this case who's mind about it</li> </ul>

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