On 1/27/11 3:54 PM, Sturla Molden wrote:
> Lists allocate empty slots at their back, proportional to their size. So
> as lists grows, re-allocations become rarer and rarer. Then on average
> the complexity per append becomes O(1), which is the "amortised"
> complexity. Appending N items to a list t
Den 28.01.2011 00:33, skrev Christopher Barker:
>
> hmmm - that doesn't seem quite right -- lists still have to
> re-allocate and copy, they just do it every n times (where n grows
> with the list), so I wouldn't expect exactly O(N).
Lists allocate empty slots at their back, proportional to thei
On 1/27/11 1:53 PM, Sturla Molden wrote:
But N appends are O(N) for lists and O(N*N) for arrays.
hmmm - that doesn't seem quite right -- lists still have to re-allocate
and copy, they just do it every n times (where n grows with the list),
so I wouldn't expect exactly O(N).
But you never kn
Den 27.01.2011 22:47, skrev Sturla Molden:
>
> Please observe that appending to a Python list is amortized O(1),
> whereas appending to a numpy array is O(N**2).
>
Sorry, one append to a numpy array is O(N).
But N appends are O(N) for lists and O(N*N) for arrays.
S.M.
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Den 27.01.2011 22:03, skrev Dewald Pieterse:
> Is numpy.append so slow? or is the culprit numpy.where?
Please observe that appending to a Python list is amortized O(1),
whereas appending to a numpy array is O(N**2).
Sturla
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NumPy-Discussion mailing
On Thu, Jan 27, 2011 at 4:33 PM, Dewald Pieterse
wrote:
>
>
> On Thu, Jan 27, 2011 at 4:19 PM, Christopher Barker > wrote:
>
>> On 1/27/11 1:03 PM, Dewald Pieterse wrote:
>>
>>> I am processing two csv files against another, my first implementation
>>> used python list of lists and list.append to
On Thu, Jan 27, 2011 at 4:19 PM, Christopher Barker
wrote:
> On 1/27/11 1:03 PM, Dewald Pieterse wrote:
>
>> I am processing two csv files against another, my first implementation
>> used python list of lists and list.append to generate a new list while
>> looping all the data including the non-re
I am processing two csv files against another, my first implementation used
python list of lists and list.append to generate a new list while looping
all the data including the non-relevant data (can't determine location of
specific data element in a list of list). So I re-implented the exact same
