plplot-general — PLplot user discussion group

Re: [Plplot-general] Compiling Plplot

[Alan W. I. <ir...@be...>]

On 2008-03-18 14:03-0000 Andrew Ross wrote:

> Alan (Irwin), do you have a clean lenny system,
> and if so can you compile the octave bindings ok?

My platform is lenny except for a sid kernel and sid X packages (which should
not affect PLplot/octave).

After your question I realized I could no longer build the octave bindings
on my (mostly) lenny system.  Here is the relevant cmake output:

-- OCTAVE = /usr/bin/octave
-- WARNING: mkoctfile not found. Disabling octave bindings

In fact the locate command confirms there is no longer any mkoctfile file on
my system.  If you search for that file at
http://www.us.debian.org/distrib/packages it turns out that it is now
located in the octave2.1-headers package. (I assume there was a decision to
move it from the octave2.1 package, and that change took effect during one
of my recent updates to lenny.)

After I installed the octave2.1-headers package on sid, the PLplot octave
bindings again can be built and (c)tested without troubles.  I would advise
the original poster to install the octave*headers package for whatever version
of octave they use, and hopefully that will also solve their issue.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________

Linux-powered Science
__________________________

Re: [Plplot-general] Compiling Plplot

[Andrew R. <and...@us...>]

Paul,

This code is interpreted by the perl matwrap script which automatically
generates the octave bindings. 

Can you just clarify whether you are running debian testing (lenny) or
debian unstable (sid). I have a debian testing system with some packages
(including octave3.0) pulled in from sid. With this I can compile 
plplot fine. The sid packages also build fine on the autobuild daemons.
If you are using sid you might like to consider testing these packages.
The latest is 5.9.0-1. Alan (Irwin), do you have a clean lenny system, 
and if so can you compile the octave bindings ok?

Are you using a clean build tree? With a moving target like debian
testing it is easy for things to change. I notice that you are missing
some of the perl modules required for octave documentation. This
shouldn't upset things, but you might like to install 
libxml-parser-perl and libxml-dom-perl just to be sure.

Regards

Andrew

On Fri, Mar 14, 2008 at 06:20:28PM +0100, Paul Wellner Bou wrote:
> Hello,
> 
> You're right. The url is not working anymore. I reproduced the error and 
> uploaded it to my server.
> 
> http://m21s26.vlinux.de/stuff/plplot-compile-error.txt
> 
> The problem is something like:
> 
> [ 45%] Generating plplot_octave.cc, tmp_stub
> Warning: unrecognized text:
> 
> void c_plcont(PLFLT **f, PLINT nx, PLINT ny, PLINT kx, PLINT lx,
>    PLINT ky, PLINT ly, PLFLT *clevel, PLINT nlevel,
>    void (*pltr) (PLFLT, PLFLT, PLFLT *, PLFLT *, PLPointer),
>    PLPointer pltr_data);
> %nowrap
> [...]
> 
> Is this code which should be interpreted by octave? Or what is to be 
> compiled here?
> 
> Could be a problem of the octave transitions. There are some broken 
> packages with octave3.0 and there is no octave3.0-forge yet.
> 
> My installed octave versions:
> 
> # apt-cache policy octave2.9
> octave2.9:
>    Installed: 1:2.9.19-2
>    Candidate: 1:2.9.19-2
>    Version table:
>   *** 1:2.9.19-2 0
>          500 ftp://ftp2.de.debian.org testing/main Packages
>          100 /var/lib/dpkg/status
>       2.9.9-8etch1 0
>          500 ftp://ftp2.de.debian.org stable/main Packages
> dorian:~# apt-cache policy octave2.9-headers
> octave2.9-headers:
>    Installed: 1:2.9.19-2
>    Candidate: 1:2.9.19-2
>    Version table:
>   *** 1:2.9.19-2 0
>          500 ftp://ftp2.de.debian.org testing/main Packages
>          100 /var/lib/dpkg/status
>       2.9.9-8etch1 0
>          500 ftp://ftp2.de.debian.org stable/main Packages
> 
> Regards
> Paul.
> 
> 
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2008.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
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> https://lists.sourceforge.net/lists/listinfo/plplot-general
> 

Re: [Plplot-general] Another conceptional issue using griddata

[Alan W. I. <ir...@be...>]

On 2008-03-14 11:01+0100 Paul Wellner Bou wrote:

>> I think yes.  Once you get plgriddata and plshades working for polar
>> coordinates it should be a simple matter to use plbox to make a rectangular
>> box around the circular area created by plshades.  You can arrange the plbox
>> call so the tick marks on the box are for rectangular coordinates
>> corresponding to the polar coordinates used for plshades.
>
> Puh... I don't understand this at this moment. I'll have to dive into
> it. Converting it to polar coordinates, ok. This should be no problem.
> Then I would get (I hope so...) a regular grid in polar coordinates. But
> if I convert it back it may not be regular, in x-y, right?

By all means, plot the plshades result in a circular area. Set up plbox to
make a square object that fits around that circular area. All my remark
meant is you will have to make the x and y tick marks of the box correspond
to r cos theta, r sin theta where r and theta are the polar coordinates.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________

Linux-powered Science
__________________________

Re: [Plplot-general] Compiling Plplot

[Paul W. B. <pa...@pu...>]

Hello,

You're right. The url is not working anymore. I reproduced the error and 
uploaded it to my server.

http://m21s26.vlinux.de/stuff/plplot-compile-error.txt

The problem is something like:

[ 45%] Generating plplot_octave.cc, tmp_stub
Warning: unrecognized text:

void c_plcont(PLFLT **f, PLINT nx, PLINT ny, PLINT kx, PLINT lx,
   PLINT ky, PLINT ly, PLFLT *clevel, PLINT nlevel,
   void (*pltr) (PLFLT, PLFLT, PLFLT *, PLFLT *, PLPointer),
   PLPointer pltr_data);
%nowrap
[...]

Is this code which should be interpreted by octave? Or what is to be 
compiled here?

Could be a problem of the octave transitions. There are some broken 
packages with octave3.0 and there is no octave3.0-forge yet.

My installed octave versions:

# apt-cache policy octave2.9
octave2.9:
   Installed: 1:2.9.19-2
   Candidate: 1:2.9.19-2
   Version table:
  *** 1:2.9.19-2 0
         500 ftp://ftp2.de.debian.org testing/main Packages
         100 /var/lib/dpkg/status
      2.9.9-8etch1 0
         500 ftp://ftp2.de.debian.org stable/main Packages
dorian:~# apt-cache policy octave2.9-headers
octave2.9-headers:
   Installed: 1:2.9.19-2
   Candidate: 1:2.9.19-2
   Version table:
  *** 1:2.9.19-2 0
         500 ftp://ftp2.de.debian.org testing/main Packages
         100 /var/lib/dpkg/status
      2.9.9-8etch1 0
         500 ftp://ftp2.de.debian.org stable/main Packages

Regards
Paul.

Re: [Plplot-general] Compiling Plplot

[Andrew R. <and...@us...>]

Hi Paul,

I'm afraid your URL doesn't work for me. Can you provide some more
details? Plplot definitely should build on debian testing. I've been 
working on the updated debian packages so I've been testing it out. 
The packages certainly build for most architectures using unstable. I
guess it might be a problem with the transition to octave 3.0?

Andrew

On Thu, Mar 13, 2008 at 10:43:12AM +0100, Paul Wellner Bou wrote:
> Hello,
> 
> I have some problems compiling Plplot 5.8 and 5.9 under linux with 
> octave bindings. I get this error:
> 
> http://rafb.net/p/CqFSKU16.html
> 
> Uninstalling octave2.9-headers (debian testing/sid) solves the compile 
> problem but I don't get the octave bindings.
> 
> Regards
> Paul.
> 
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2008.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Plplot-general mailing list
> Plp...@li...
> https://lists.sourceforge.net/lists/listinfo/plplot-general
> 

Re: [Plplot-general] Another conceptional issue using griddata

[Paul W. B. <pa...@pu...>]

Hello again,

I thought about other possibilities... well, the nicest way would be a 
triangulation working like the matlab griddata function. As the griddata 
in matlab is a compiled mex file and the source not published I can't 
have a look inside it.

There are a few workarounds...

1) Using polar coordinates as Alan Irwin suggested. Using this method I 
have to trust the triangulation alogrithm of plplot to work right with 
more or less rectangular data.

2) As this is a ray (wave front) tracing result it would be possible to 
calculate the rays in a way to produce a rectangular grid. As side 
effect I would save calculation time: As the intersections of rays and 
spline surfaces is done by iterations (newton) I would save this step if 
I define the intersections before and just calculate then the resulting 
direction. Concerning this fact, an interesting idea.

3) Converting the circular eye glass blanks to rectangles. Calculating 
the rays through them and using plgriddata to calculate the regular 
grid. As in 1) I have to assume that the plgriddata function works 
everytime as expected. I could cut the points outside the circle off, 
later, before drawing them and before defining the contour levels.

Perhaps the best way would be a mixture between 2) and 3). Using a 
rectangular spot with rays going through a rectangular eye glass.

I'll try...
Thanks very much and regards
Paul.

Re: [Plplot-general] Another conceptional issue using griddata

[Paul W. B. <pa...@pu...>]

Hello,

Thank you for your answer.

> Since your pattern of points is confined to a circular area (and rather
> complete within that area), my suggestion is to try using polar coordinates
> throughout.  Now example 21 obviously uses rectangular coordinates for
> plgriddata, but I presume plgriddata should work just as it is for any
> two-dimensional coordinate system.

Yes, this should work. I will have a look. Not sure if there is the time 
to implement this. Perhaps it is easier to calculate the rays which 
intersect with the eye glass in exactly the points of a rectangular grid.

>  Furthermore, example 16's last page (see
> http://plplot.sourceforge.net/examples-data/demo16/x16.05.png) shows
> plshades can be used with any two-dimensional coordinate system.

Ok, this looks good. This example shows me that it is possible to draw a 
graph of a circle without filling the whole rectangle.

>> Is there a way to use the DTLI algorithm to get a kind of data like in
>> http://m21s26.vlinux.de/math/gsg.png?
> 
> I think yes.  Once you get plgriddata and plshades working for polar
> coordinates it should be a simple matter to use plbox to make a rectangular
> box around the circular area created by plshades.  You can arrange the plbox
> call so the tick marks on the box are for rectangular coordinates
> corresponding to the polar coordinates used for plshades.

Puh... I don't understand this at this moment. I'll have to dive into 
it. Converting it to polar coordinates, ok. This should be no problem. 
Then I would get (I hope so...) a regular grid in polar coordinates. But 
if I convert it back it may not be regular, in x-y, right?
Hm, not sure how to implement this, but it should be possible in any way.

Thank you and regards
Paul.

Re: [Plplot-general] Another conceptional issue using griddata

[Arjen M. <arj...@wl...>]

Paul Wellner Bou wrote:

> Hello,
>
>> Quite apart from the suggestion by Alan, what platform are you 
>> working on?
>
>
> I am working on windows. I am starting now to test the code I wrote on 
> windows as the final application is targeted mainly for windows 
> systems (the company who will use the software is using windows). But 
> I did not try Plplot with windows yet.
>
>> I have seen this type of problems before on Windows, but we (the 
>> original author and me) have not been able to figure out why this 
>> happened.
>>
>> Perhaps it is time to revisit this issue (in the near future at 
>> least) ...
>
>
> Would be great... not sure if I will find time to dive into this, but 
> I would like to.
>
> Best regards
> Paul.
>
Hi Paul,

the various gridding options are part of one of the examples - that 
shows the
effects and would be the starting ground for any code diving, I'd say.
(Apart from this issue, if it still exists, PLplot is doing fine on 
Windows ;))

Regards,

Arjen

Re: [Plplot-general] Another conceptional issue using griddata

[Arjen M. <arj...@wl...>]

Paul Wellner Bou wrote:

>Hello,
>
>as you might have seen, after some days of trying around I am now able 
>to create a regular grid with griddata().
>
>Now, using griddata, I have to decide which gridding algorithm to use. 
>As I used the delauny triangulation method in Matlab before, I would 
>like to use this one with Plplot, too.
>
>But using GRID_DTLI (Delaunay Triangulation Linear Interpolation) I get 
>a regular grid full of NaNs. Thats fine, but not what I need.
>
>As the cubic spline method is another possible way to get "good" data, I 
>tried this one, too. I get a half NaN matrix. The rest of the values are ok.
>
>The linear interpolation algorithm is too bad for my case.
>
>Well, my data is from a wavefront tracing through an eye glass blank. So 
>the result points (x, y, z) in the x-y-layer are those: 
>http://m21s26.vlinux.de/math/datapoints.png
>So I would understand if there are a lot of NaNs around the data.
>
>Is there a way to use the DTLI algorithm to get a kind of data like in 
>http://m21s26.vlinux.de/math/gsg.png?
>  
>
Quite apart from the suggestion by Alan, what platform are you working on?
I have seen this type of problems before on Windows, but we (the original 
author and me) have not been able to figure out why this happened.

Perhaps it is time to revisit this issue (in the near future at least) ...

Regards,

Arjen

Re: [Plplot-general] Another conceptional issue using griddata

[Alan W. I. <ir...@be...>]

On 2008-03-13 16:54+0100 Paul Wellner Bou wrote:

> Hello,
>
> as you might have seen, after some days of trying around I am now able
> to create a regular grid with griddata().
>
> Now, using griddata, I have to decide which gridding algorithm to use.
> As I used the delauny triangulation method in Matlab before, I would
> like to use this one with Plplot, too.
>
> But using GRID_DTLI (Delaunay Triangulation Linear Interpolation) I get
> a regular grid full of NaNs. Thats fine, but not what I need.
>
> As the cubic spline method is another possible way to get "good" data, I
> tried this one, too. I get a half NaN matrix. The rest of the values are ok.
>
> The linear interpolation algorithm is too bad for my case.
>
> Well, my data is from a wavefront tracing through an eye glass blank. So
> the result points (x, y, z) in the x-y-layer are those:
> http://m21s26.vlinux.de/math/datapoints.png
> So I would understand if there are a lot of NaNs around the data.

Since your pattern of points is confined to a circular area (and rather
complete within that area), my suggestion is to try using polar coordinates
throughout.  Now example 21 obviously uses rectangular coordinates for
plgriddata, but I presume plgriddata should work just as it is for any
two-dimensional coordinate system.  Furthermore, example 16's last page (see
http://plplot.sourceforge.net/examples-data/demo16/x16.05.png) shows
plshades can be used with any two-dimensional coordinate system.

>
> Is there a way to use the DTLI algorithm to get a kind of data like in
> http://m21s26.vlinux.de/math/gsg.png?

I think yes.  Once you get plgriddata and plshades working for polar
coordinates it should be a simple matter to use plbox to make a rectangular
box around the circular area created by plshades.  You can arrange the plbox
call so the tick marks on the box are for rectangular coordinates
corresponding to the polar coordinates used for plshades.

Good luck with the polar-coordinate implementation along the lines I have
suggested.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________

Linux-powered Science
__________________________

[Plplot-general] Another conceptional issue using griddata

[Paul W. B. <pa...@pu...>]

Hello,

as you might have seen, after some days of trying around I am now able 
to create a regular grid with griddata().

Now, using griddata, I have to decide which gridding algorithm to use. 
As I used the delauny triangulation method in Matlab before, I would 
like to use this one with Plplot, too.

But using GRID_DTLI (Delaunay Triangulation Linear Interpolation) I get 
a regular grid full of NaNs. Thats fine, but not what I need.

As the cubic spline method is another possible way to get "good" data, I 
tried this one, too. I get a half NaN matrix. The rest of the values are ok.

The linear interpolation algorithm is too bad for my case.

Well, my data is from a wavefront tracing through an eye glass blank. So 
the result points (x, y, z) in the x-y-layer are those: 
http://m21s26.vlinux.de/math/datapoints.png
So I would understand if there are a lot of NaNs around the data.

Is there a way to use the DTLI algorithm to get a kind of data like in 
http://m21s26.vlinux.de/math/gsg.png?

Thanks very much.
Regards
Paul.

Re: [Plplot-general] Using griddata with C++

[Paul W. B. <pa...@pu...>]

Got it.
Another error. nn must be <= n.

Thanks anyway.

Regards
Paul.

Re: [Plplot-general] Using griddata with C++

[Paul W. B. <pa...@pu...>]

Hello again,

i discovered an error and now I am able to use the 2-dimensional array 
zg right.

The problem is still the griddata function. Something is wrong there. 
The running program is killed calling the griddata function.

Regards, Paul.

P.S.: My actual Code: (cd is a ContourableData object which extends 
Contourable_Data).

	pls = new plstream();
	pls->init();
	
	PLFLT *x, *y, *z;
	PLINT n = cd.count();
	x = cd.get_x();
	y = cd.get_y();
	z = cd.get_value();
	
	const PLINT nn = 20;
	PLFLT *xg = new PLFLT[nn];
	PLFLT *yg = new PLFLT[nn];
	PLFLT **zg;
	pls->plAlloc2dGrid(&zg, nn, nn);
	
	double step = 2*28/((double)n-1);
	for(int i = 0; i < nn; i++){
		double val = -28 + step*(double)i;
		xg[i] = val;
		yg[i] = val;
	}
	
	pls->griddata(x, y, z, n, xg, nn, yg, nn, zg, GRID_DTLI, 0.0);

[Plplot-general] Using griddata with C++

[Paul W. B. <pa...@pu...>]

Hello,

i am trying to create a regular grid with the griddata function of 
Plplot. I followed the example file x21.cc and the griddata documentation.

But there is a problem in my code and I don't find the reason. There is 
no error message, just the message that the program is exiting with 
return value -1. Nothing more.

My code:


====================================================================
	plstream *pls;
	pls = new plstream();
	pls->init();
	
	PLFLT *x, *y, *z;
	int n = cd.count();
	x = cd.get_x();
	y = cd.get_y();
	z = cd.get_value();
	
	int nn = 20;
	PLFLT *xg = new PLFLT[nn];
	PLFLT *yg = new PLFLT[nn];
	PLFLT **zg;
	pls->Alloc2dGrid(&zg, nn, nn);
	
	double step = 2*28/((double)n-1);
	for(int i = 0; i < n; i++){
		double val = -28 + step*(double)i;
		xg[i] = val;
		yg[i] = val;
	}

	pls->griddata(x, y, z, n, xg, nn, yg, nn, zg, GRID_DTLI, 0);
====================================================================


Is there a problem in this code?

I tried to check zg with this lines:


====================================================================
	for(int i = 0; i < nn; i++){
		for(int j = 0; j < nn; j++){
			cout << "\t";
			cout << zg[i][j];
		}
		cout << "\n";
	}
====================================================================


Using the Debian testing/sid Plplot 5.6.1 I get an error message:


*** glibc detected *** /home/paul/dev/opsc/opsc/Debug/opsc: corrupted 
double-linked list: 0x080a2fa0 ***
======= Backtrace: =========
[...]


And a big 20x20 matrix output of zeros. This is what it should be, I 
suppose. But why the glibc error then?

I hope someone can help me here. Thanks very much and best regards,

Paul.

[Plplot-general] Compiling Plplot

[Paul W. B. <pa...@pu...>]

Hello,

I have some problems compiling Plplot 5.8 and 5.9 under linux with 
octave bindings. I get this error:

http://rafb.net/p/CqFSKU16.html

Uninstalling octave2.9-headers (debian testing/sid) solves the compile 
problem but I don't get the octave bindings.

Regards
Paul.

Re: [Plplot-general] filled contour plots with irregular data

[Paul W. B. <pa...@pu...>]

Hello,

Thank you for the answer. Yes, I thought about using octave for this. 
The problem is that I was not able to reproduce the Matlab graphs with 
octave, neither using gnuplot nor octplot nor plplot.

And the final application has to be easily installable on windows 
machines, and I don't want to force them to install octave first.

Regards
Paul.

Re: [Plplot-general] filled contour plots with irregular data

[Paul W. B. <pa...@pu...>]

Hi,

Thanks very, very much for your answer.

> Would plgriddata do what you need?
> http://plplot.sourceforge.net/docbook-manual/plplot-html-5.9.0/plgriddata.html

Yes, I think thats exactly what I want. The "Delaunay Triangulation
Linear Interpolation" method should do a fine job for my case. But I'll
try the cubic spline method, too.

> plshades (or multiple calls to plshade) can generate the actual plot.
> http://plplot.sourceforge.net/docbook-manual/plplot-html-5.9.0/plshades.html

Thank you. I'll have a closer look at plshade this weekend to understand
what this is really doing.

> PLplot does not have a built-in function to draw a color bar.  I have
> written a simple one in OCaml which can probably be translated to
> C/C++ without a lot of trouble:

No problem. color bar is not the most important thing. Could be drawn
otherwise, too. But thanks for the suggestion.

> I think plvect will do what you want here.
> http://plplot.sourceforge.net/docbook-manual/plplot-html-5.9.0/plvect.html
> plsvect can change the arrow style, and will hopefully give you what you want.

Great. Looks like what I want. I'll try it and report.

Thank you very much.
Paul.

Re: [Plplot-general] Plotting in X11 apps

[Andrew R. <and...@us...>]

On Fri, Mar 07, 2008 at 05:43:43PM +0100, Fons Adriaensen wrote:
> On 16 Feb I wrote:
> 
> > ...
> > 
> > Now I'm trying to find out how to use Plplot purely
> > as a plotting library in existing X11 apps.
> > 
> > What I need is a function that will draw a 3D plot to
> > window or a pixmap using either the basic X11 backend
> > or Cairo, and nothing more. Setting up any resources
> > and calling the function at the right time is the
> > application's responsability. The drawing routing is
> > not expected to create the window, wait for X events
> > etc., and in fact must not do any of this.
> > 
> > ...
> 
> There were no useful answers, so this means I'll
> have to abandon plplot - a pity since the output
> produced is quite nice.

Fons,

You might like to look at the mem device. This might do what you want.
Interestingly enough there is someone else currently looking on plotting
direct to an X Drawable which sounds even more like what you want. You
can find the relevant thread and patch on the plplot-devel mailing list.
There is an archive at
http://sourceforge.net/mailarchive/forum.php?forum_name=plplot-devel

This uses Cairo to produce the output, which provides better font
support amongst other things.

Andrew

[Plplot-general] Plotting in X11 apps

[Fons A. <fo...@ko...>]

On 16 Feb I wrote:

> ...
> 
> Now I'm trying to find out how to use Plplot purely
> as a plotting library in existing X11 apps.
> 
> What I need is a function that will draw a 3D plot to
> window or a pixmap using either the basic X11 backend
> or Cairo, and nothing more. Setting up any resources
> and calling the function at the right time is the
> application's responsability. The drawing routing is
> not expected to create the window, wait for X events
> etc., and in fact must not do any of this.
> 
> ...

There were no useful answers, so this means I'll
have to abandon plplot - a pity since the output
produced is quite nice.

Ciao,

-- 
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

Lascia la spina, cogli la rosa.

Re: [Plplot-general] filled contour plots with irregular data

[Alan W. I. <ir...@be...>]

On 2008-03-07 14:23+0100 Paul Wellner Bou wrote:

> Hello,
>
> i am writing a program in C++ where I am implementing the stuff I
> developed my thesis about eye glass optics with Matlab/Octave. I tried a
> C++ interface to gnuplot, but as the interface is not very nice and as I
> did not find this feature there until now, I am trying the C++ PLPlot
> interface right now.

There is an octave interface to PLplot that is normally built as part of the
PLplot build.  This interface includes complete access to low-level PLplot
commands (see the octave implementation of all the PLplot standard examples
at bindings/octave/demos/x??c.m) as well as higher-level plotting
functionality (see bindings/octave/demos/p*.m for a a number of examples of
this functionality).  Anyhow, I suggest you try the octave interface to
PLplot since it does have enhanced capabilities, and you do seem to be quite
familiar with Matlab/Octave.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________

Linux-powered Science
__________________________

Re: [Plplot-general] filled contour plots with irregular data

[Hezekiah M. C. <hc...@at...>]

On Fri, Mar 7, 2008 at 8:23 AM, Paul Wellner Bou <pa...@pu...> wrote:
> Hello,
>
>  i am writing a program in C++ where I am implementing the stuff I
>  developed my thesis about eye glass optics with Matlab/Octave. I tried a
>  C++ interface to gnuplot, but as the interface is not very nice and as I
>  did not find this feature there until now, I am trying the C++ PLPlot
>  interface right now.
>
>  I need to draw graphs like those: http://m21s26.vlinux.de/math/gsg.png
>
>  The data does not fit in a regular grid, so there has to be a kind of
>  triangulation or something similar. In Matlab I use the function
>  griddata for this. The lines to draw this graphs in Matlab are following:
>
>  lmin = min(min(Zi));
>  lmax = max(max(Zi));
>  levels=[lmin:min(.1,(lmax-lmin)/100):lmax];
>  [C,h] = contourf(Xi,Yi,Zi,levels,'LineStyle','none');
>  axis equal;
>  colorbar;
>  grid on;
>
>  Is there a way to do this with PLPlot? And if there is, how? Is this
>  possible with the plstream::fcont method? Does PLPlot implement some
>  kind of triangulation or do I have to write this on my own?

Would plgriddata do what you need?
http://plplot.sourceforge.net/docbook-manual/plplot-html-5.9.0/plgriddata.html

PLplot comes with several gridding methods, and I have used it for a
few simple tests.

plshades (or multiple calls to plshade) can generate the actual plot.
http://plplot.sourceforge.net/docbook-manual/plplot-html-5.9.0/plshades.html
PLplot does not have a built-in function to draw a color bar.  I have
written a simple one in OCaml which can probably be translated to
C/C++ without a lot of trouble:
http://code.google.com/p/ocaml-plplot/source/browse/trunk/extras.ml -
color_bar at line 77 uses color map 1 (continuous colors) and
color_bar0 at line 137 uses color map 0 (indexed colors).  The OCaml
plplot functions follow the C functions pretty closely.

This is an example of what a color_bar0 color bar looks like:
http://www.atmos.umd.edu/~hcarty/precip_maps/August/trmm_august_climatology.png
color_bar would be similar.

>  Another issue: Is there a way to draw "quiver" graphs like this one?
>  http://m21s26.vlinux.de/math/achs.png
>  (In this case I multiplied the arrow length of the points with the z value.)

I think plvect will do what you want here.
http://plplot.sourceforge.net/docbook-manual/plplot-html-5.9.0/plvect.html
plsvect can change the arrow style, and will hopefully give you what you want.

I am new to PLplot as well, so these may not be the best methods
available.  They should help with what you need though.

Hez

-- 
Hezekiah M. Carty
Graduate Research Assistant
University of Maryland
Department of Atmospheric and Oceanic Science

[Plplot-general] filled contour plots with irregular data

[Paul W. B. <pa...@pu...>]

Hello,

i am writing a program in C++ where I am implementing the stuff I 
developed my thesis about eye glass optics with Matlab/Octave. I tried a 
C++ interface to gnuplot, but as the interface is not very nice and as I 
did not find this feature there until now, I am trying the C++ PLPlot 
interface right now.

I need to draw graphs like those: http://m21s26.vlinux.de/math/gsg.png

The data does not fit in a regular grid, so there has to be a kind of 
triangulation or something similar. In Matlab I use the function 
griddata for this. The lines to draw this graphs in Matlab are following:

lmin = min(min(Zi));
lmax = max(max(Zi));
levels=[lmin:min(.1,(lmax-lmin)/100):lmax];
[C,h] = contourf(Xi,Yi,Zi,levels,'LineStyle','none');
axis equal;
colorbar;
grid on;

Is there a way to do this with PLPlot? And if there is, how? Is this 
possible with the plstream::fcont method? Does PLPlot implement some 
kind of triangulation or do I have to write this on my own?

Another issue: Is there a way to draw "quiver" graphs like this one? 
http://m21s26.vlinux.de/math/achs.png
(In this case I multiplied the arrow length of the points with the z value.)

Thank you very, very much for any hints. And sorry for this quite 
general questions.

Regards
Paul Wellner Bou

Re: [Plplot-general] Numeric label problem

[Kaj W. <kaj...@ik...>]

2008/3/5, Bruno Picard <bp...@cl...>:
>  maybe you should have a look on plsxax and plsyax that set the number of digits for the respective axis labels.

That worked, thanks!

In fact I used plprec(1,1) but the idea is the same.

Cheers,
Kaj

Re: [Plplot-general] Numeric label problem

[Kåre E. <ke...@ni...>]

I'm not sure, but I think the "plenv ()" call wants 4 major ticks. If
you use 2006 instead of 2005 it will work...
This also goes for the "plwind ()" call, so I think it's a general thing
that graphics bokses wants at least 4 major ticks to display proper.

I agree it's a bug...

Cheers,
Kåre

On Wed, 2008-03-05 at 12:41 +0200, Kaj Wiik wrote:

> Forgot to mention library version:
> 5.6.1-11ubuntu1 (gutsy)
> 
> 2008/3/5, Kaj Wiik <kaj...@ik...>:
> > Hi!
> >
> >  There seems to be a bug in the algorithm that determines the numeric
> >  labes for axes. It is easier to show than explain.. This code:
> >
> >  use PDL;
> >  use PDL::Graphics::PLplot;
> >
> >  plinit();
> >  plenv(2003, 2005, 2003, 2005, 0, 0);
> >  plend;
> >
> >  produces these labels:
> >
> >                    |
> >   2005        +
> >                    |
> >   2005        +
> >                    |
> >   2004        +
> >                    |
> >   2004        +
> >                    |
> >   2003   ----+--------+--------+--------+--------+---
> >                 2003    2004     2004     2005     2005
> >
> >  I guess they should read "2003  2003.5  2004  2004.5  2005".
> >
> >  Any suggestions?
> >
> >  Thanks,
> >
> > Kaj
> >
> 
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Re: [Plplot-general] Numeric label problem

[Bruno P. <bp...@cl...>]

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<html>
<head>
  <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Hi Kaj,<br>
<br>
maybe you should have a look on <tt>plsxax</tt> and <tt>plsyax</tt>
that set the number of digits for the respective axis labels.<br>
<br>
Bruno<br>
<br>
Kaj Wiik a &eacute;crit&nbsp;:
<blockquote
 cite="mid:33a...@ma..."
 type="cite">
  <pre wrap="">Hi!

There seems to be a bug in the algorithm that determines the numeric
labes for axes. It is easier to show than explain.. This code:

use PDL;
use PDL::Graphics::PLplot;

plinit();
plenv(2003, 2005, 2003, 2005, 0, 0);
plend;

produces these labels:

                   |
  2005        +
                   |
  2005        +
                   |
  2004        +
                   |
  2004        +
                   |
  2003   ----+--------+--------+--------+--------+---
                2003    2004     2004     2005     2005

I guess they should read "2003  2003.5  2004  2004.5  2005".

Any suggestions?

Thanks,
Kaj

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<br>
<div class="moz-signature">-- <br>
<div align="center"><u>____________________________________________________</u>
<br>
<font face="Verdana" size="2"> Dr. Bruno Picard <br>
<br>
CLS<br>
Dir. Oc&eacute;anographie Spatiale, D&eacute;p. Traitement de la Mesure et Segment
Sol <br>
<i>Space Oceanography Division, Data Analysis and Ground Processing Unit</i><br>
<br>
8-10 rue Herm&egrave;s, 31520 Ramonville Saint Agne, France<br>
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