[Scilab-users] feedback on removing 1 row and 1 column

[Stéphane Mottelet]

Le 30/04/2019 à 08:44, Carrico, Paul a écrit :
>
> Dear All
>
> I’ve been using successfully Scilab for years, to develop my projects; 
> I do not remember if I’ve ever had to deal with huge matrixes but 
> that’s the case today.
>
> Using “csvRead”, I got a matrix with 2.3 million of rows and 6 columns 
> (it took about 240 seconds to read it J); nevertheless I’ve been 
> surprised when I tried to remove the first row and the last column 
> using basically:
>
This one is quasi instantaneous, although it needs to move all the 
variable content in memory
>
> MAT(1,:) = [];
>
But this stucks Scilab, you are right:
>
> MAT(:,$) = [];
>
athough it should the faster of both (large number of rows but no copy 
needed, trim the block in memory should be enough).

@Samuel: I think we already have something similar signaled in Bugzilla

S.

> Indeed I needed to kill the process after about 10 minutes (same 
> result both under Windows 10 and Linux – RAM not fully used).
>
> By comparison, the same process is instantaneous under Python using 
> Numpy (numpy.delete) using of course the same matrix.
>
> A feedback I wanted to share ….
>
> PaulEXPORT CONTROL :
>
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-- 
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet

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