Re: [Maxima-discuss] Memory-efficient arrays

[Stavros M. <mac...@al...>]

Your application -- purely numeric -- sounds like a good use case for R
rather than Maxima. With R + plyr + ggplot2, you can easily do large
numerical manipulations and plot them beautifully in a few lines of code.


On Thu, Apr 17, 2014 at 4:05 AM, Gunter Königsmann <gu...@pe...>wrote:

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> Dear all,
>
> I am currently using Maxima for visualization of and calculations with
> real data from oscilloscopes.
> Normally this data is in a semicolon-separated file of the format
>
> time;Channel 2;Channel 3;Channel 4;Channel 5
> time;Channel 2;Channel 3;Channel 4;Channel 5
> time;Channel 2;Channel 3;Channel 4;Channel 5
> ...
>
> with 10000 to 1000000 lines. Currently I use read_matrix from the
> package numericalio to read the data. But I would be willing to
> convert everything into another format if that is necessary.
>
> I then put the data from the 1..100 individual files a measurement
> series is made up from into an array of lists with the format similar
> to the following:
>
> nolabels:true;
> measurementseries:makelist(
>   block(
>     [data],
>     data:transpose(read_matrix(filename))
>     [
>       time=list_matrix_entries(row(data,1)),
>       ch1=list_matrix_entries(row(data,2)),
>       ch2=list_matrix_entries(row(data,3)),
>       ch3=list_matrix_entries(row(data,4)),
>       ch4=list_matrix_entries(row(data,5))
>     ]
>   ),
>   filename,
>   [
>     "filename1",
>     "filename2",
>     "filename3",
>     "filename4",
>     "filename5"
>   ]
> )
> I rather like the object-orientied approach to keep all information a
> measurement is made up from together.
>
> Unfortunately tend to run out of memory much quicker than I thought
> hoping that every number would use 64 Bits of memory plus a little bit
> of overhead for every list I create (even with nolabels:true and
> declaring all temporary variables to be temporary by block()
> commands.) ...and the whole thing is slower than I would like it to, too.
>
> Is here a significantly more efficient way to deal with big lists of
> numbers in maxima?
>
> Thanks a lot,
>
>   Gunter.
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