gnuplot-beta

Pseudofile for vectors

[Peter D. <pc...@wi...>]

I'd like to detect whether plot/splot has been called 'with vectors'
and generate an extra column of data from the pseudofile '+'.

Problem is that by the time df_generate_pseudodata() is called,
df_current_plot isn't set; so I can't simply check whether
df_current_plot->plot_style == VECTOR.

Is there any other way to determine the plot style other than mucking
around in the option parser to set a global?


P.S. The attached patch dodges the issue entirely by simply producing
two columns of data; but this results in superfluous data for
one-variable functions.

Re: Pseudofile for vectors

[Ethan A M. <merritt@u.washington.edu>]

On Saturday 08 December 2007 02:09, Peter Danenberg wrote:
> I'd like to detect whether plot/splot has been called 'with vectors'
> and generate an extra column of data from the pseudofile '+'.

Hmm. Does it really need an extra column of pseudodata?
What were you going to put there?
I understand that you need additional columns in the using specifier,
but I don't see how you could autogenerate these from the x/y grid
sampling.  Aren't they entirely specific to the function you are plotting?
For example, this isn't a very useful plot but it show that you can 
generate vector plots:

   plot [-8:8] '+' using ($1):(sin($1)):(cos($1)):(sin($1)) with vector
 
> Problem is that by the time df_generate_pseudodata() is called,
> df_current_plot isn't set; so I can't simply check whether
> df_current_plot->plot_style == VECTOR.

Heh.  Until about 2 days ago, df_current_plot was _never_ set, except
in the one special case of 2D histograms.  Earlier this week I realized 
by consistently setting df_current_plot from df_open(), not only could
the histogram code be cleaned up but also two outstanding bugs could be
fixed.  So as of 5 December, df_current_plot should be available for
all plots to check.   Please try again using current CVS.

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742

Re: Pseudofile for vectors

[Peter D. <pc...@wi...>]

On Sat, Dec 08, 2007 at 03:24:32PM -0800, Ethan A Merritt wrote:
> Does it really need an extra column of pseudodata?

You need two dimensions of sampling for something like this:

    http://wikisophia.org/wiki/User:Danenberg#Vector_field

That hack was only possible by splotting to get an extra column out of
'+', and flattening to 2d with `set view map':

    splot '+' using 1:2:(0.0):(cos($1)):(cos($2)):(0.0) with vectors

Problem is that for 3d vectorfields, there's no 4d analog of splot to
flatten into a cube.