Newcomer to Python tutorial question

Chris Rebert clp2 at rebertia.com
Thu May 7 21:08:51 CEST 2009


On Thu, May 7, 2009 at 11:58 AM, Alan Cameron <alan.cameron at iname.com> wrote:
> "Alan Cameron" <alan.cameron at iname.com> wrote in message
> news:hRFMl.50224$tb.4955 at newsfe07.ams2...
>>I am not sure of this is the right place to ask a question about the
>>tutorial
>>
>> http://docs.python.org/3.0/tutorial/datastructures.html#sets
>>
>> why is the printed result of
>>
>>>>> basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}
>>>>> print(basket)
>> {'orange', 'banana', 'pear', 'apple'}
>>
>> in the sequence given?
>>
>>
>
> Thanks to all who replied.
> I assume therefore that the order in which the items of the set are printed
> could vary each time it is printed?

Due to the underlying dict-based implementation, the order will stay
the same until you modify the set (i.e. add or remove an element), at
which point it may change; it's basically the same behavior as with
printing a dict.

So this will always print the same thing twice:
print basket
print basket

Whereas this might not:
print basket
#modify the set
basket.discard("banana")
basket.add("banana")
print basket

Cheers,
Chris
-- 
http://blog.rebertia.com



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