Re: [Gnuplot-info] Plot matrix with GNUplot. Slow

[walter h. <wh...@bf...>]

I am ot sure that i understand your problem
do you want to plot something like a heatmap ?
i routinely plot 4000 * n via plot matrix with no problem

re,
 wh

Am 17.05.2013 22:36, schrieb Yonghui:
> Hi Ethan,
> 
> Thanks for your suggestion. I tried every. But it didn't work. For example:
> If the file (test.txt) is :
> 1 1 1 1
> 2 1 1 1
> 3 1 1 1
> 4 1 1 1
> 
> 1 2 2 2
> 2 2 2 2
> 3 2 2 2
> 4 2 2 2
> 
> 1 3 3 3
> 2 3 3 3
> 3 3 3 3
> 4 3 3 3
> 
> Then set pm3d, set view map, unset surf
> The sp "test.txt" matrix ind 0 is exactly what I need. But I completely have
> no idea on how to use every to make the same plot. If I do sp "test.txt"
> matrix every :::0::0, it doesn't make anything.
> 
> Could you please tell me how to make it work?
> 
> Thanks,
> Yonghui
> 
> -----Original Message-----
> From: Ethan A Merritt [mailto:eam...@gm...] 
> Sent: Friday, May 17, 2013 12:54 AM
> To: Yonghui
> Cc: gnu...@li...
> Subject: Re: [Gnuplot-info] Plot matrix with GNUplot. Slow
> 
> On Thursday, 16 May 2013, Yonghui wrote:
>> Thanks Ethan,
>>
>> I am actually making a movie. 200 pictures, each picture is the 
>> 100x100 matrix. Here is the command:
>  
>> ------------plot_TDM_loop.gp"----------------
>> splot '_TDTDM.dat' matrix ind i*10
>> print i
>> i=i+1
>> if (i<200) reread
>>
>> Please take a look. Thanks.
> 
> Ugh. 
> So it opens the file all over again each time, reads one line at a time
> until it gets to where it finished during the previous iteration, then reads
> one matrix and loops again.  That means the time goes up as N^2 rather than
> N.
> 
> I'm not certain, but I would guess that it would be faster if instead of
> using
>   splot $FOO matrix index i*10        (By the way, why 10?  Why not 100?)
> you used
>   splot $FOO matrix every 1:1:1:i::i
> 
> I may have mangled that "every" specfier right; you may have to tweak it.
> See "help every".
> The idea is that in order to read the Nth block you should skip the
> preceding N-1 blocks altogether rather than processing
> them line-by-line.   It still has to read in the data, but it
> won't bother to parse the contents of the lines you skip.
> 
> But really I think a better idea is to split the input into N separate files
> and then iterate over which file is read.
> That way it goes back to O(N) rather than O(N^2).
> 
> If you split the data into files file1.dat file2.dat ... fileN.dat your loop
> could look like this
> 
> set pm3d
> unset surface
> set view map
> set palette defined (-0.01 "red", 0 "white", 0.01 "blue") do for [i=1:N] { 
>     splot 'file' . i . '.dat' matrix;
> }
> unset out
> 
> 
> 	Ethan
> 
> 
>>
>> Yonghui
>>
>> -----Original Message-----
>> From: Ethan A Merritt [mailto:eam...@gm...]
>> Sent: Friday, May 17, 2013 12:18 AM
>> To: gnu...@li...
>> Cc: FortCpp
>> Subject: Re: [Gnuplot-info] Plot matrix with GNUplot. Slow
>>
>> On Thursday, 16 May 2013, FortCpp wrote:
>>> I am using GNUplot for plotting a small matrix. The matrix is 
>>> 100x100 by size. e.g.
>>>
>>> 1.23212 2.43123 -1.24312 ......
>>> -4.23123 2.00458 5.60234 ......
>>> ......
>>> The data is not neatly stored in the file. So from C++ point of 
>>> view, due to the lack of length per data, there is no way to load a 
>>> whole number, but it has to check when the number is loading. I 
>>> guess this should be the reason of the slow plotting speed.
>>>
>>> Now I have 3 questions:
>>> Q1: Is loading the bottle neck?
>>>
>>> Q2: If I can make the data file neatly stored (setw). e.g.
>>>
>>>  1.23212  2.43123 -1.24312 ......
>>> -4.23123  2.00458  5.60234 ......
>>> ......
>>> Does the plotting speed get any improvement? (Maybe GNUplot can 
>>> check what the pattern is. Thus improve the loading speed. Not 
>>> sure.)
>>
>> No. That won't make any difference.
>>
>>>
>>> Q3: Any other options that I can set to make it faster?
>>
>> gnuplot> help fpe
>>
>>  The `set datafile nofpe_trap` command tells gnuplot not to 
>> re-initialize a floating point exception handler before every 
>> expression evaluation used while  reading data from an input file.  
>> This can significantly speed data input from  very large files at the 
>> risk of program termination if a floating-point  exception is generated.
>>
>> You haven't shown us the commands you use to read the file, so I don't 
>> know if this is relevant to your case.
>>
>> There is a recent patch in the CVS version that hugely speeds up 
>> reading binary matrices, but since the matrix you show is in ascii 
>> that wouldn't help.
>>
>> 	Ethan
>>
>>
>> --
>> Tradition is not the worship of ashes, but the preservation of fire.
>>   - Gustav Mahler
>>
>>
> 
> 
> --
> Tradition is not the worship of ashes, but the preservation of fire.
>   - Gustav Mahler
> 
> 
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