Re: [Gnuplot-info] Background depending on data

[Ethan A M. <eam...@gm...>]

On Saturday, 02 June 2018 07:14:17 theozh wrote:
> Hello,
> I am trying to create a plot with background color depending on a datafile. The datafile basically just contains 0s and 1s for "off" and "on". When it is "on" the background should be e.g. a light green and should span the whole y-range of the plot.
> I tried with fillstep and calculate the ymin and ymax using the 0s and 1s from the data file and GPVAL_Y_MIN and GPVAL_Y_MAX. That's why I apparently have to use "replot" to get the actual (autoscaled) values.
> The script below seem to work in general but for some strange reason not always. Sometimes the GPVAL_Y_MIN and GPVAL_Y_MAX values do not correspond to the y-axis minimum and maximum.
> Furthermore, the fillstep fills always to 0, not from ymin to ymax.
> Maybe I am just thinking too complicated and there is a function to do this much simpler?
> Any ideas? Thank you.

My take is
   set linetype 101 lc bgnd
   set linetype 102 lc "seagreen"
   set boxwidth 1.0
   set yrange [0:*]
   BIGNUM = 1.e5

   plot $Data using ($1+0.5):(BIGNUM):($2==0?101:102) with boxes lc var noautoscale, \
        whatever-the-foreground-plot-is

If ymin < 0 you would have to tweak this a bit.
Maybe draw the boxes twice, once with +BIGNUM once with -BIGNUM.
Or use boxxy, but that requires a more complicated using spec.

	Ethan



> 
> I put the following script into a loop so that you can try several times and see that it sometimes works sometimes not...
> 
> # gnuplot script: local background depending on data
> reset
> $Data <<EOD
> 1 0
> 2 0
> 3 1 
> 4 1
> 5 0
> 6 0
> 7 0
> 8 1
> 9 1
> 10 1
> 11 1
> 12 0
> 13 0
> 14 0
> 15 0
> EOD
> set colorsequence classic
> 
> do for [i=1:100] {
>     A = rand(0)*100
>     B = rand(0)*100
>     plot A*sin(x) + B
>     set label 1 sprintf("A: %g\nB: %g\nGPVAL_Y_MIN: %g\nGPVAL_Y_MAX: %g",A,B,GPVAL_Y_MIN,GPVAL_Y_MAX) at screen 0.5,0.5 noenhanced
>     replot $Data u 1:((GPVAL_Y_MAX - GPVAL_Y_MIN)*$2 + GPVAL_Y_MIN) w fillsteps fs transparent solid 0.1
>     pause -1 "Press Enter to next plot"
> }
> # end gnuplot script
> 
> 
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