Best way to plot lines with variable color?

[Jim Kleckner-8]

What would be the recommended way to plot line segments with varying
color (a multicolored single line plot)?

The 4.2 documentation says that "rgbcolor variable" "is only available
in 3D plotting mode (splot)".

The 4.3 documentation doesn't mention this restriction.

Can 4.3 take the color of line segments from a column of data?

Is there any way to do this simply (or not) in 4.2.5?

Thanks!

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[Jim Kleckner-8]

Jim Kleckner wrote:
 > What would be the recommended way to plot line segments with varying
 > color (a multicolored single line plot)?
 >
 > The 4.2 documentation says that "rgbcolor variable" "is only available
 > in 3D plotting mode (splot)".
 >
 > The 4.3 documentation doesn't mention this restriction.
 >
 > Can 4.3 take the color of line segments from a column of data?
 >
 > Is there any way to do this simply (or not) in 4.2.5?
 >
 > Thanks!


I got around to compiling the CVS/4.3 version of Gnuplot
and line segments do work with color.

However the demo script below works for png files but
gives the following error for pdf files:
  fatal exception: [2100] PDF_lineto: Function must not be called in
'page' scope

Anyone run into this or suggest where to start?

I'm running:
   gnuplot from cvs sources as of today.
   PDF-Lib-Lite-7.0.4p4 (updated to freshest to test this)
   CYGWIN_NT-5.1 kleckner2 1.5.25(0.156/4/2) 2008-06-12 19:34 i686 Cygwin

Thanks!

PS, I'm still curious if someone knows of a way to plot 2D line segments
with color even in 4.2 gnuplot.



============= greenblackred.dem =============
#
# colorspec demo for line segments
#
# greenblackred.dat:
# 1 0 65280
# 2 1 0
# 3 0 16711680
# 4 1 0
# 5 0 65280
# 6 1 0
# 7 0 16711680
# 8 1 0
# 9 0 65280
#
set terminal png
set output "greenblackred.png"
reset
set xrange [ 0 : 10 ]
#plot 'greenblackred.dat' using 1:2 with lines                     title
"simple sawtooth"
plot 'greenblackred.dat' using 1:2:3 with lines lc rgb variable   title
"variable sawtooth"
set terminal pdf
set output "greenblackred.pdf"
plot 'greenblackred.dat' using 1:2 with lines                     title
"simple sawtooth"
plot 'greenblackred.dat' using 1:2:3 with lines lc rgb variable   title
"variable sawtooth"


# plotcurves.py
#
# colorspec demo for line segments
#
# greenblackred.dat:
# 1 0 65280
# 2 1 0
# 3 0 16711680
# 4 1 0
# 5 0 65280
# 6 1 0
# 7 0 16711680
# 8 1 0
# 9 0 65280
#
set terminal png
set output "greenblackred.png"
reset
set xrange [ 0 : 10 ]
#plot 'greenblackred.dat' using 1:2 with lines                     title "simple sawtooth"
plot 'greenblackred.dat' using 1:2:3 with lines lc rgb variable   title "variable sawtooth"
set terminal pdf
set output "greenblackred.pdf"
plot 'greenblackred.dat' using 1:2 with lines                     title "simple sawtooth"
plot 'greenblackred.dat' using 1:2:3 with lines lc rgb variable   title "variable sawtooth"


1 0 65280
2 1 0
3 0 16711680
4 1 0
5 0 65280
6 1 0
7 0 16711680
8 1 0
9 0 65280

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[Jim Kleckner-8]

Jim Kleckner wrote:
> Jim Kleckner wrote:
>  > What would be the recommended way to plot line segments with varying
>  > color (a multicolored single line plot)?

...

> However the demo script below works for png files but
> gives the following error for pdf files:
>  fatal exception: [2100] PDF_lineto: Function must not be called in
> 'page' scope
>
> Anyone run into this or suggest where to start?

FYI, after getting pango/cairo upgraded, the simple pdf example worked
with the terminal type "pdfcairo".

So I guess the issue is with the pdf terminal.

However, pdfcairo has inconsistent fonts when substituted for pdf
terminal and other issues...


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