Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.graphics.apps.gnuplot > #1560

Re: Image or special files do not work on y2 axis?

Followups directed to: comp.graphics.apps.gnuplot

Show all headers | View raw

Ingo Thies wrote:

> Dear all,
> 
> I am currently trying to trick a gradient fill below a curve by the
> following method:
> 
> f(x)=-x*x+1.
> xmin=-1.;xmax=1.
> ymin=0.;ymax=1.2
> set xrange [xmin:xmax];set cbrange [xmin:xmax]
> set y2range [0:1]#dummy yrange
> #set palette defined ( 0 "blue", 3 "green", 6 "yellow", 10 "red" )
> set palette file 'RGB_palettes/rainbow.gpf' u 1:2:3:4; set xrange
> [xmin:xmax];set cbrange [xmin:xmax]
> #set yrange [ymin:ymax]#actual yrange using y2 axis
> set yrange [0:*]
> unset colorbox
> unset y2tics; set ytics autofreq
> plot '++' using 1:2:1 axes x1y2 with image,\
> f(x) axes x1y1 notitle w filledcurves below y1=ymax lc rgb "white",\
> f(x) axes x1y1 t 'f(x)' w l lc rgb "#000000"
> 
> While this works without problem for the "palette defined ..." method
> it fails for "palette file ...", with an error message "y range is
> invalid". However, if I exchange y1 and y2 axes it works. My guess:
> gnuplot can define file dummy files of the type '++' and similar
> properly only if axes x1y1 is used. Otherwise the palette
> specification fails. Did I found a bug here? Or is there a bug in the
> script above?

I believe the problem is that autoscaling (set yrange [0:*])
cannot be combined with either sampling (plot '++' ...) 
It requires an explicit range over which the samples are generated.

If I add an explicit range before the plot command so that the sampling
is well defined, then I find that your plot command works with either the
the y1 or y2 axis.

set palette defined ...   # either this
set palette file ...      # or this

plot [xmin:xmax][ymin:ymax] '++' using 1:2:1 axes x1y2 with image,\
f(x) axes x1y1 notitle w filledcurves below y1=ymax lc rgb "white",\
f(x) axes x1y1 t 'f(x)' w l lc rgb "#000000"

pause -1

plot [xmin:xmax][ymin:ymax] '++' using 1:2:1 axes x1y1 with image,\
f(x) axes x1y2 notitle w filledcurves below y2=ymax lc rgb "white",\
f(x) axes x1y2 t 'f(x)' w l lc rgb "#000000"

I don't think the palette definition is relevant here.

Back to comp.graphics.apps.gnuplot | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Image or special files do not work on y2 axis? Ingo Thies <ingo.thies@gmx.de> - 2012-12-29 15:06 +0100
  Re: Image or special files do not work on y2 axis? sfeam <sfeam@users.sourceforge.net> - 2012-12-29 14:15 -0800
    Re: Image or special files do not work on y2 axis? Ingo Thies <ingo.thies@gmx.de> - 2012-12-30 11:12 +0100
      Re: Image or special files do not work on y2 axis? sfeam <sfeam@users.sourceforge.net> - 2012-12-31 12:09 -0800
        Re: Image or special files do not work on y2 axis? Ingo Thies <ingo.thies@gmx.de> - 2013-01-01 13:36 +0100

csiph-web