[Scilab-users] Why so slow?

[Michael Dunn]

I had a whole slew of CSV problems too - over a year ago. Guess they
haven't been fixed yet.


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-----Original Message-----
From: Richard Llom <richard.llom at gmail.com>
Reply-To: "International users mailing list for Scilab."
<users at lists.scilab.org>
Date: Tuesday, May 20, 2014 2:44 PM
To: "users at lists.scilab.org" <users at lists.scilab.org>
Subject: [Scilab-users] Why so slow?

>Hello,
>I need to read in a csv of about 360.000 lines with date and numerical
>values. Attached is a sample excerpt of that file.
>
>So far I did:
>==== CODE ====
>
>// read in
>tic
>mydat = csvRead('dat04-2011.csv', ';', ',', 'double', [], [], [], 6);
>toc (= 5,213 secs)
>mydat = mydat(:,2:6);
>tic
>mystring = csvRead('dat04-2011.csv', ';', ',', 'string', [], [], [], 6);
>toc (= 3,077 secs)
>mystring = mystring(:,1);
>
>
>tic
>for i=1:size(mydat,1)
>    mydate(i,:) = strtod(strsplit(mystring(i,1),['.';' ';':']))';
>end
>toc (= 186,473 secs)
>
>
>==== CODE ====
>(I filled in the toc values).
>
>
>As you can see this is unfortunately very slow. The read in of the csv,
>but 
>especially the for loop.
>
>So I have several question:
>
>1)
>Is there a faster way to read in the csv? Note that I need the 'header'
>option.
>
>2)
>Instead of the loop I would like to use
>mydate = strtod(strsplit(mystring(:,1),['.';' ';':']))';
>but this doesn't work. Is there another way to avoid the loop?
>
>3)
>The raw csv file is around 15MB, but when I want to read it in the second
>time, Scilab says this will exceed the stacksize. Which is default by
>76MB. 
>So I don't quite understand how two times the 15MB file takes so much
>memory? I raised the stacksize now, but I would rather like not to.
>
>
>Any help is appreciated.
>Thanks!
>Richard