Re: [Gnuplot-info] Smooth with filledcurves

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

On Saturday, 12 October 2013 06:36:47 AM Brynolf wrote:
> Hello, 
> 
> I want to use smoothing with the filledcurves plot, but I am unable to do
> so. When I add smooth csplines to the command it will only consider the
> first two columns and disregard the third column and plot a line, not two
> lines with filled center, so to speak. Any help appreciated

Consider only the part of the command you ask about:

> plot 'data.dat' using 1:($4-sqrt($5)):($4+sqrt($5)) w filledcu notitle smooth csplines

There are 2 or 3 problems here.
One is fairly simple:

The "smooth csplines" must come immediately after the "using ...." part
of the command.  So you would need to move the "with filledcurve" to the end:

?  plot 'data.dat' using 1:($4-sqrt($5)):($4+sqrt($5)) smooth csplines w filledcu

However a bigger problem is that the "smooth" operation _replaces_ your
original data with a new curve defined by only an x value from the first
"using" column and a smoothed y value from the second "using" column.
The third "using" column is ignored, and no longer exists after the smoothing
operation.  This confuses the "with filledcurves" command, so we'll call it 
a bug that the program does not issue some error or warning message.

If you remove the third "using" column,  you'll see better what is happening:

? plot 'data.dat' using 1:($4-sqrt($5)) smooth csplines w filledcu

That command does give you a filled curve from the smoothed data,
but of course it's not quite the curve you wanted.

Possibly this two-part solution is acceptable:

  plot "data.dat" using 1:($4+sqrt($5)) smooth csplines w filledcu lc rgb "black", \
         "" using 1:($4-sqrt($5)) smooth csplines w filledcu lc rgb "white"

That wouldn't quite work in the general case, but it works in your case because
we know that y-sqrt(foo) is always less than y+sqrt(foo) so the second curve
is strictly less or equal to the first curve.

	Ethan


> ! My code:
> 
> set terminal pngcairo
> set output 'plotData.png'
> set style fill transparent solid .1 noborder
> 
> plot "data.dat" using 1:2 title "avg" smooth csplines lc rgbcolor "blue",\
> 	"" using 1:($2-sqrt($3)) notitle smooth csplines lc rgbcolor "blue",\
> 	"" using 1:($2+sqrt($3)) notitle smooth csplines lc rgbcolor "blue",\
> 	"" using 1:4 title "mag" smooth csplines ls 1 lc rgbcolor "red",\
> 	"" using 1:($4-sqrt($5)):($4+sqrt($5)) w filledcu notitle smooth csplines
> lc rgbcolor "black"
> 
> with data.dat containing:
> 30	0.062091	        0.00055934	0.062135	        0.00060258
> 35	1.5811		0.0011609	1.4886		0.34498
> 40	5.7981		0.0022667	5.466		        4.768
> 45	2.9185		0.0014332	2.7366		1.1653
> 50	1.0325		0.0027071	0.97853		0.14908
> 55	0.95136		0.0030296	0.90318		0.12694
> 60	1.1746		0.0022948	1.1095		0.19144
> 65	1.1357		0.0024049	1.0738		0.17953
> 100	0.81919		0.0037934	0.78151		0.095113
> 125	0.76154		0.0040944	0.72843		0.082592
> 150	0.70832		0.0044431	0.67914		0.071776
> 
> 
> 
> --
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