Tuple question

Colin J. Williams cjw at sympatico.ca
Thu Sep 2 20:36:40 CEST 2004



Wai Yip Tung wrote:
> Oops I misunderstood that you said about count and index. Now I got it.
> 
> Speaking as a user of Python, here is my take:
> 
> You consider tuple an immutable version of list. But in Python's design  
> they have different purpose. List a collection of homogeneous items, 
> while  tuple is  a convenient grouping of any kind of items. For 
> example, you can  use them this way:
> 
> users = ['admin', 'user1', 'user2']
> address = ('www.python.org', 80)
> 
> index and count only make sense when the collection is homogeneous.  
What about:

addresses= list(address)
print addresses
users.append(address)
print users

Colin W.
> Therefore they are not defined for tuple.
> 
> tung
> 
> On Thu, 02 Sep 2004 17:40:27 +0100, Will McGugan  
> <news at NOwillmcguganSPAM.com> wrote:
> 
>> Wai Yip Tung wrote:
>>
>>> I'm not sure what do you mean by index. But you can use len() to get  
>>> the  number of objects in a tuple. e.g.
>>>
>>>>>> t=(1,2,3)
>>>>>> len(t)
>>>
>>>  3
>>>
>>>>>> t[2]
>>>
>>>  3
>>>
>>
>> Lista have an index method that returns the index of the first 
>> occurance  of an element, but tuple doesnt (nor count). Just wondering 
>> why.
>>
>>  >>> l= [ 1, 2, 3 ]
>>  >>> t= ( 1, 2, 3 )
>>  >>> l.index(2)
>> 1
>>  >>> t.index(2)
>> Traceback (most recent call last):
>>    File "<pyshell#8>", line 1, in ?
>>      t.index(2)
>> AttributeError: 'tuple' object has no attribute 'index'
> 
> 



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