[Numpy-discussion] appending extra items to arrays

Chad Kidder cckidder@gmail....
Wed Oct 17 07:58:50 CDT 2007


Growing an array by appending it is the slow way in matlab.  The  
suggested way to do things there is preallocate the array by saying  
x=zeros(....) and then referencing the elements in the array and  
inserting the correct value.


--Chad Kidder


On Oct 17, 2007, at 7:16 AM, mark wrote:

> So it seems like lists are the way to grow an array.
>
> Interestingly enough, it is very easy to grown an array in Matlab.
> Any idea how they do that (or are they slow as well?).
>
> Mark
>
> On Oct 11, 8:53 pm, "Adam Mercer" <ramer...@gmail.com> wrote:
>> On 11/10/2007, Mark Janikas <mjani...@esri.com> wrote:
>>
>>> If you do not know the size of your array before you finalize it,  
>>> then
>>> you should use lists whenever you can.  I just cooked up a short
>>> example:
>>
>> <snip>
>>
>>> ##### Result #####
>>> Total Time with array: 2.12951189331
>>> Total Time with list: 0.0469707035741
>>> #################################################################### 
>>> ####
>>> ####
>>
>>> Hope this helps,
>>
>> That is helpful, I thought that using arrays would be much faster but
>> its clearly not in this case.
>>
>> Thanks
>>
>> Adam
>> _______________________________________________
>>

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