Re: Speed of odsread

[hjborsje]

I assume you are using this code [1]? Java is not as native to Octave as it
is to Matlab (the whole GUI is Java), so any attempt to use Java is
overhead. I tried  the odsread function from the io package [2]. But the
results are not promising as well. To use, just type:

>> pkg install -forge io
>> pkg load io
>> javaaddpath ("jOpenDocument-1.3.jar")          # Available from [3]
>> javaaddpath ("xerces-2_11_0/xercesImpl.jar") # Available from [4]

>> N = 10; t = 0; for i = 1:N, tic; X = odsread ('RData_01b.ods'); t = t +
>> toc; end, fprintf('csvread: avg. %f seconds\n', t/N)

csvread: avg. 10.013385 seconds

It is a bit time saving, when having multiple reads to open the document
once and only invoke the reading, but not that much better:

>> ods = odsopen ('RData_01b.ods'); N = 10; t = 0; for i = 1:N, tic; X =
>> ods2oct (ods); t = t + toc; end, fprintf('csvread: avg. %f seconds\n',
>> t/N), ods = odsclose (ods);

csvread: avg. 7.611418 seconds


Anyway, when dealing with a huge amount of data, I think that an Excel- or
ODS-spreadsheet is like running a marathon in   knight's armor, it is an
unnecessary overhead. Simply save your data from your application of choice
as comma separated values (CSV) and see the magic that works even far beyond
60,000 data rows:

>> N = 10; t = 0; for i = 1:N, tic; X = csvread ('RData_01b.csv'); t = t +
>> toc; end, fprintf('csvread: avg. %f seconds\n', t/N)

Matlab R2017a: csvread: avg. 0.014881 seconds
Octave 4.2.1: csvread: avg. 0.020552 seconds

Kai.

[1]:
https://www.mathworks.com/matlabcentral/fileexchange/28411-read-and-write-open-document-format--odf--spreadsheet---ods-
[2]: https://octave.sourceforge.io/io/function/odsread.html
[3]: http://www.jopendocument.org/downloads.html
[4]: https://xerces.apache.org/mirrors.cgi#binary



I was using [2], with similar results as you do.  I read somewhere that
starting with Octave 4.0 all Java was native in Octave.  I guess that line
could use some clarification, I'm no Java user. After installing the two
Java jars I also get the faster times.

csv is clearly the way to go, but sometimes it's easier to pick a few
numbers from specific cells in a spreadsheet.

Henk




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