2

I am writing a MATLAB program that exports MATLAB plots to tikz code. One of the features that I find very useful and that I would also like to implement is the specification of the surface color. In MATLAB one would usually run the code

surfc(X,Y,Z,C)

where [X,Y]=meshgrid(x,y) are meshgrids of the vectors x,y, Z=f(X,Y) is some function of these meshgrids, and C is the surface color data. In the pgfplots manual, the author states that the data X,Y,Z can be exported using the code:

XX=X'; YY=Y'; ZZ=Z';
data = [ XX(:) YY(:) ZZ(:) ]
save P.dat data -ASCII

This can be found in the pgfplots manual on page 538. However, this export neglects the surface color data found in C. In some simulations C can be something different than the typical z-axis, e.g. C = X.*Y (Note .* is the equivalent of the Hadamard product in MATLAB). Is there a way to consider this quantity in pgfplots? If so how can it be exported and integrated into the code?

In general, my question can be divided into two parts:

  1. Is there a way to export C in order to specfiy the surface color data and set the colorbar axis? Preferably some way like this:
XX=X'; YY=Y'; ZZ=Z' CC = CC';
data = [ XX(:) YY(:) ZZ(:) CC(:)]
save P.dat data -ASCII
  1. Does pgfplots accepts this? If so, how can I use the exported data? (small example would be helpful)

To clarify what I mean with 2) I will provide a small example. When the data X,Y,Z are exported, one can use the code

\addplot3[surf,mesh/cols=10,mesh/ordering=rowwise,shader=interp] file {P.dat};.

to plot the surf data. How does the above code line change if the color data is additionally exported?

1 Answer 1

1

Interestingly, I was able to find the answer through trial and error. For anyone interested in this type of work, all you have to do is use my suggested code:

XX=X'; YY=Y'; ZZ=Z' CC = CC';
data = [ XX(:) YY(:) ZZ(:) CC(:)]
save P.dat data -ASCII

Then by expanding the addPlot command as follows:

\addplot3[surf,mesh/cols=10,mesh/ordering=rowwise,shader=interp, point meta = explicit] file {P.dat};

one obtains the desired result, i.e. the surface is colored according to the fourth column in the exported table. The keyword point meta = explicit tells pgf that the table has the following structure

xcol    ycol    zcol     colordata

Hence, pgf directly knows how to color the surface and where to find the information. Very nice feature, which is sadly not explicitly mentioned for surf plots in the pgf manual. I guess it is a feature that should be discerned by the reader.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .