Optimizing Inner Loop Copy

[Mark E. Fenner]

Mark E. Fenner wrote:

> John Machin wrote:
> 
>> 
>> Mark E. Fenner wrote:
>> 
>>> Here's my class of the objects being copied:
>> 
>> Here's a couple of things that might help speed up your __init__
>> method, and hence your copy method:
>> 
>>>
>>> class Rule(list):
>>>     def __init__(self, lhs=None, rhs=None, nClasses=0, nCases=0):
>> 
>>     def __init__(self, lhs=None, rhs=(), nClasses=0, nCases=0):
>> 
>>>         self.nClasses = nClasses
>>>         self.nCases = nCases
>>>
>>>         if lhs is not None:
>>>             self.extend(lhs)
>> what does the extend method do? If it is small, perhaps inline a copy
>> of its code here.
>>>
>>>         if rhs is None:
>>>             self.rhs=tuple()
>>>         else:
>>>             self.rhs=rhs
>> 
>> Replace the above 4 lines by:
>>     self.rhs = rhs
>>  
>> HTH,
>> John
> 
> John,
> 
> Thanks.  I thought of those at the same you did!  I also incorporated one
> other use of the default=() + no conditional:
> 
> class Rule(list):
>     def __init__(self, lhs=(), rhs=(), nClasses=0, nCases=0):
>         self.nClasses = nClasses
>         self.nCases = nCases
>         self.extend(lhs) # note, self is a list so this is list.extend
>         self.rhs=rhs
> 
>     def copy(self):
>         return Rule(self,
>                     self.rhs,
>                     self.nClasses,
>                     self.nCases)


Actually, I also removed the "passthrough" that copy was doing and just
called the constructor directly.  So, at the top level code, we have:

allNew = []
for params in cases:
    # newobj = initialObject.copy()
    newObj = Rule(initialObject, initialObject.rhs,
                  initialObject.nClasses, 
                  initialObject.nCases)
    newObj.modify(params)
    allNew.append(newObj)
return allNew

Regards,
Mark