Christophe:

Thank you, I suspected that there must have been a method like copy, but 
didn't know what it was.

Ken



On Wednesday, March 12, 2014 5:01:21 PM UTC-4, projetmbc wrote:
>
> Hello.
>
> This is certainly due to the way Python manages unhashable variables. If 
> you type p6 is c6, you will obtain True, in other words, p6 and c6 are 
> two references to the same object.
>
> Using p6=c6.copy() will do the job.
>
> Best regards.
> Christophe BAL
>
>
> 2014-03-12 21:42 GMT+01:00 Ken Levasseur <[email protected] <javascript:>>:
>
>> I want to examine graphs I get by removing single edges from an initial 
>> graph and I've run into a problem.  Here it is:
>>
>> For example, I start with 
>>
>> c6=graphs.CycleGraph(6)
>> a=c6.edges()[0]
>> p6=c6
>> p6.delete_edge(a)
>>
>>
>> Now if I do this:
>>
>> p6.is_tree()
>>
>>
>> I get the output I expect,  True.
>>
>> However, if evaluate the following, I also get True
>>
>> c6.is_tree()
>>
>>
>> Removing the edge from p6 also removes it from c6.  So p6 and c6 seem to 
>> be pointers to the same structure.  How do I create a truely new graph out 
>> of the original?
>>
>> Ken Levasseur
>> UMass Lowell 
>>
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