lists and append, and loop iteration
Mark Krischer
mkrisch at radiata.com
Wed Sep 22 03:32:27 EDT 1999
this might be a newbie a question, but is there a reason why append
doesn't create a list if the list doesn't exist?
it seems to add a bit of complexity to have to do something like:
dict = {}
if 'new_key' not in dict.keys():
dict['new_key'] = [new_value]
else:
dict['new_key'].append(new_value)
it seems like i should just be able to say "list.append(new_value)" and
if list doesn't exist,
i get "list[0] = [new_value]
am i missing something fundamental that this would completely break?
and while i'm bending your ear, let me ask a second question.
if i do:
for element in list:
do something with element
is there any to find out what my current index is? i've basically been
doing something like:
list.index(element)
this happens to work fine for what i'm doing now, but only because i
don't care about doubles in the list, but should that ever be a problem,
how will i know which element i'm dealing with.
i figure i can always do:
for i in range(len(list)):
do something with list[i]
but it just feels like i should be able to things the other way as well.
thoughts?
thanks in advance.
--mk
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