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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Thank you to <st1:PersonName w:st="on">Sam</st1:PersonName>uel
Gougeon, these do appear to be the commands I need, will try them.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Dave<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><b><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-weight:bold'>Subject:</span></font></b> <a
href="mailto:users@lists.scilab.org?subject=Re:%20Re:%20reading%20or%20loading%20big%20files">Re:
reading or loading big files</a> <br>
<b><span style='font-weight:bold'>From:</span></b> <a
href="http://lists.scilab.org/cgi-bin/?list=users&cmd=author&authorid=kbhiaakjapnpjgklnkji&month=201006">Samuel
Gougeon ####@####.####</a> <br>
<b><span style='font-weight:bold'>Date:</span></b> 7 Jun 2010 11:18:33 +0200 <br>
<b><span style='font-weight:bold'>Message-Id:</span></b>
<4C0CB964.90207@univ-lemans.fr> <o:p></o:p></p>
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<pre><font size=2 face="Courier New"><span style='font-size:10.0pt'>Hello,<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'><o:p> </o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>----- Message d'origine -----<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>De : <st1:PersonName
w:st="on">Hsu</st1:PersonName> (David)<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>Date : 05/06/2010 08:20:<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> I am just learning SciLab. I need to read enormous EEG files <o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> (electroencephalograms), for example, 20 channels sampled at 32,000 Hz <o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> for days on end. This data may be saved as a matrix with 20 columns <o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> but a huge number of rows, so big that I run up against size limits if <o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> I try to load the whole thing as a matrix. This data is usually in <o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> binary format. I tried using stacksize('max') to maximize these size <o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>> limits but am still running into size limits.<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>A simple calculation:<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>20 channels x 32000 measurements/s/channel x 1 byte/measurement<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>x 3600x24 s/day ~ 55 Gbytes/day<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>If you want to load the whole data as a int8() or uint8() matrix<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>(as minimal data format), you need at least ~ 60 Gbytes of RAM.<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>Do you have it (assuming that Scilab or another software could handle it)?<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>It looks unrealistic to load and handle these data as a whole into a matrix.<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>You will likely need to use some detailled binary commands<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'>after mopen() : mseek(), mtell(), mget()... to read some piece of data.<o:p></o:p></span></font></pre><pre><font
size=2 face="Courier New"><span style='font-size:10.0pt'><o:p> </o:p></span></font></pre><pre><st1:PersonName
w:st="on"><font size=2 face="Courier New"><span style='font-size:10.0pt'>Sam</span></font></st1:PersonName>uel<o:p></o:p></pre>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> <st1:PersonName
w:st="on">Hsu</st1:PersonName> (David) <br>
<b><span style='font-weight:bold'>Sent:</span></b> Saturday, June 05, 2010 1:21
AM<br>
<b><span style='font-weight:bold'>To:</span></b> users@lists.scilab.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> reading or loading big
files</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Tahoma><span style='font-size:
10.0pt;font-family:Tahoma;color:black'>I am just learning SciLab. I need
to read enormous EEG files (electroencephalograms), for example, 20 channels
sampled at 32,000 Hz for days on end. This data may be saved as a matrix
with 20 columns but a huge number of rows, so big that I run up against size
limits if I try to load the whole thing as a matrix. This data
is usually in binary format. I tried using stacksize('max') to maximize
these size limits but am still running into size limits.</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'>Is there a way to load or read in just a part of this huge
matrix, process that, then go back and load or read the next chunk? </span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'>Thank you.</span></font><o:p></o:p></p>
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