Ishwor wrote: ...
I believe lamda's are unnamed functions aren't they?? Still learning... ;-)
Yes.
yeah actually i saw what Fedrik had to say above. I created a sliced
copy of the l & did my homework within the for loop
You might want to check it again before you hand it in ;) ...
>>> def ishwor( source ):
... for item in source:
... if item == 'd':
... source.remove( item )
... >>> d = ['a','b','c','d','e']
>>> ishwor( d )
>>> d
['a', 'b', 'c', 'e']
Well, that worked fine, but wait a minute...
>>> d = ['a','b','c','d','d','e'] >>> ishwor( d ) >>> d ['a', 'b', 'c', 'd', 'e']
This is the same problem as you saw before. Under the covers, the Python interpreter is written such that it's keeping track of the index into the list as an integer. When you mutate the list, that integer gets out-of-sync with the value you think you're processing.
The while form I provided avoids that by re-scanning the *whole* list every time it does the check. The filtering forms do it by working on a temporary list. The reverse-index form does it by only deleting from the segment of the list *after* the point where the to-be-done indices reference.
This code is so clean and looks very healthy. :) Python will live aCute is, of course, the highest praise to which any man, woman or language can aspire :) .
long way because its a cute language. :-)
It's actually *good* for huge lists where you only want to delete a few items, that's it's main attraction, it doesn't copy the list at all (though each deletion causes a memcopy of all pointers from that element in the list onward, that's a fairly faster operation). It's going to avoid new memory allocation much of the time, and doesn't have the "scan the whole list for each deletion" overhead of the "while x in list" version.thanx Mike, i have tried this C-ish way as well . :-) it seemed quietefor index in xrange( len(source)-1, -1, -1 ): if source[i] == 'e': del source[i]
ok for my small list but dont know about huge lists.
Anyway, have fun, Mike
________________________________________________ Mike C. Fletcher Designer, VR Plumber, Coder http://www.vrplumber.com http://blog.vrplumber.com
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