In gnuplot how can I set rgb colour from 3 columns? - colors

I have 3 'columns' in my data file that specify the red, green, and blue fractions:
red green blue
0.263 0.914 0.086
0.263 0.914 0.086
0.263 0.914 0.086
1.000 0.571 0.429
1.000 0.571 0.429
How can I use these to plot some other columns painted by these values?
Apparently the following method is only available in 3D plots with splot:
rgb(r,g,b)=<some function code>
plot './data.csv' u 1:2:(rgb($8,$9,$10)) w l rgb variable
I can't see how I can use these values to colour the plot.

Have a look at the gnuplot demo rgb_variable.dem. The corresponding data file looks like this:
0 0 0 0x000000
255 0 0 0xff0000
255 255 0 0xffff00
255 255 255 0xffffff
0 255 255 0x00ffff
255 0 255 0xff00ff
0 255 0 0x00ff00
#<snip>
#...
#</snip>
Note that the 4th column isn't used until the last example -- i.e. this is almost what you have. You'll have an additional transform to take your colors from the range [0-1] to the range [0-255], but that's an easy one (just multiply by 255):
scale(x)=x*255
rgb(r,g,b) = int(scale(r))*65536 + int(scale(g))*256 + int(scale(b))
plot './data.csv' u 1:2:(rgb($8,$9,$10)) with lines linecolor rgb variable
# ^^^^^^^^^ don't forget this:-)

Related

How to plot energy diagram using gnuplot

I have data file:
0 0 3 -0.17 6 -0.05
0 0 3 -0.23 6 0.90
0 0 3 -0.41 6 0.50
0 0 3 -0.50 6 -0.33
0 0 3 -0.20 6 0.80
I want to plot the figure like this which connects each point in the lines. Can you tell me how?
The following suggestion uses the plotting styles with boxxyerror, with vectors and with labels.
The zero level gets the color of the last entry because everything is plotted on top of each other. Check the following example as starting point for further tweaking.
Script:
### energy diagram
reset session
$Data <<EOD
0 0 3 -0.17 6 -0.05 A_{one}
0 0 3 -0.23 6 0.90 B_{two}
0 0 3 -0.41 6 0.50 C_{three}
0 0 3 -0.50 6 -0.33 D_{four}
0 0 3 -0.20 6 0.80 E_{five}
EOD
set key noautotitle
set xrange [-1:8]
myWidth = 0.3
plot for [i=1:3] $Data u (column(2*i-1)):(column(i*2)):(myWidth):(0):0:xtic(i*2-1) w boxxy lw 3 lc var, \
for [i=1:2] '' u (column(2*i-1)+myWidth):(column(i*2)): \
(column(2*i+1)-column(2*i-1)-2*myWidth):(column(i*2+2)-column(i*2)):0 w vec nohead lw 1 dt 3 lc var, \
'' u 5:6:7:0 w labels offset 6,0 tc var font ",16"
### end of script
Result:
Addition:
From your comments: If the levels are to close such that the labels overlap, you could add an individual offset (here in column 8).
Check the following example where the data is modified that the levels B and E are very close.
Script:
Edit after OP's comment: simplifications, with xerrorbar instead of with boxxyerror and with custom xtics
Edit 2: simplified input data
reduce the input data to the minimum
add xticlabel from columnheader
use column number as x-coordinate. Mind the difference in ...$Data u (col):col:...: e.g. if col=1, (col) is the fixed value of 1, and col is the value from column 1.
### energy diagram with individual offset of labels
reset session
$Data <<EOD
A B C Label Offset
0.0 -0.17 -0.05 A_{one} 0
0.0 -0.23 0.90 B_{two} 0.05
0.0 -0.41 0.50 C_{three} 0
0.0 -0.50 -0.33 D_{four} 0
0.0 -0.20 0.85 E_{five} -0.05
EOD
set key noautotitle
set errorbars 0
set offset 0.5,0.5,0,0
myWidth = 0.1
plot for [col=1:3] $Data u (col):col:(myWidth):0:xtic(columnhead(col)) w xerr lw 3 ps 0 lc var, \
for [col=1:2] '' u (col+myWidth):col:(1-2*myWidth):(column(col+1)-column(col)):0 \
w vec nohead lw 1 dt 3 lc var, \
'' u (3+myWidth):($3+$5):4:0 w labels left offset 1,0 tc var font ",16"
### end of script
Result:

Drawing polygons with holes using Gnuplot

Is there a way using Gnuplot 5.0 to plot a polygon with a hole with filledcurves?
Here are my test data:
# Outer ring
0 -2
-2 0
0 2
2 0
0 -2
# Inner ring
-0.5 0.5
-0.5 -0.5
0.5 -0.5
0.5 0.5
-0.5 0.5
And here is the result:
I know I could re-order the vertices in order to hide the connecting line (in fact the polygon frontier) between the outer and inner ring. But I will deal with machine-generated data, and I would prefer minimize the amount of data preprocessing.
In some other drawing programs, we can draw holes inside polygons by changing the winding-rule to even-odd. But I didn't find such option in gnuplot.
Finally, I cannot just draw the "hole" in white, since in my application I have several shapes to draw, And I want to see other shapes behind the "hole".
Why not just plot the hole in white on top of the shape?
Separate your date into
# shape.txt
0 -2
-2 0
0 2
2 0
0 -2
and
# hole.txt
-0.5 0.5
-0.5 -0.5
0.5 -0.5
0.5 0.5
-0.5 0.5
and then use
plot "shape.txt" u 1:2 w filledcurves, 'hole.txt' u 1:2 w filledcurves lc 'white'
The following solution does what you already mentioned in your question: It reorders the points of the inner polygon in such a way, that the endpoint of the outer polygon and the starting point of the inner polygon have minimal distance (hence no line across the inner polygon). It does is automatically with gnuplot only, so this still might be an acceptable solution for you.
Assumptions:
the outer curve is closed (start point = end point)
the outer curve does not have duplicated points
Procedure:
go through the data and when the first x and y values are found again, the outer structure is finished and the inner structure starts (row index stored in idx0)
when the inner structure starts, it looks for the minimum distance to the start/end point of the outer structure (x0,y0) (row index stored in idx1)
the data is plotted into a datablock $Hollow: first the outer as is and then the inner starting from idx1 to end, and then the inner starting from (idx0+2) to idx1.
In the example below red lines are drawn first to illustrate the empty polygon in the center. Tested with gnuplot 5.0.0.
For multiple holes in a filled curve you might want to check gnuplot: How to draw a filled area with hole? with a rather general but pretty lengthy solution.
Code:
### draw hollow polygon
reset session
$Data <<EOD
# Outer ring
0 -2
-2 0
0 2
2 0
0 -2
# Inner ring
-0.5 0.5
-0.5 -0.5
0.5 -0.5
0.5 0.5
-0.5 0.5
EOD
Distance(x0,y0,x1,y1) = sqrt((x1-x0)**2 + (y1-y0)**2)
GetIdxs(colX,colY) = LastOuter==1 ? ( d1=Distance(x0,y0,column(colX),column(colY)), \
d0==d0 ? (d1<dmin ? (idx1=column(0), dmin=d1) : 0) : \
(idx1=column(0),dmin=d1), d0=d1, LastOuter) : \
column(0)==0 ? (d0=d1=dmin=NaN,x0=column(colX),y0=column(colY)) : \
column(colX)==x0 && column(colY)==y0 && LastOuter==0 ? \
(idx0=column(0),x0=column(colX),y0=column(colY),LastOuter=1 ) \
: LastOuter
set table $Dummy
plot LastOuter=0 $Data u 1:2:(GetIdxs(1,2)):(d1) w table
set table $Hollow
plot $Data u 1:2 every ::::idx0 w table
plot $Data u 1:2 every ::idx1 w table
plot $Data u 1:2 every ::idx0+2::idx1 w table
unset table
plot for [i=-5:5] -x+i/5.lw 2 lc "red" notitle, \
$Hollow u 1:2 w filledcurves lc 1
### end of code
Result:
Just for better understanding the content of $Dummy and $Hollow.
$Dummy
0 -2 -2 nan
-2 0 0 nan
0 2 0 nan
2 0 0 nan
0 -2 1 nan
-0.5 0.5 1 2.54951
-0.5 -0.5 1 1.58114
0.5 -0.5 1 1.58114
0.5 0.5 1 2.54951
-0.5 0.5 1 2.54951
$Hollow
0 -2
-2 0
0 2
2 0
0 -2
-0.5 -0.5
0.5 -0.5
0.5 0.5
-0.5 0.5
-0.5 -0.5
My other solution is based on reordering the inner curve in order to avoid the connection line from outer to inner curve crossing the open area. However, this was rather cumbersome with dummy and extra tables and with a lengthy, confusing expression.
Here is a another much simpler solution:
It is based on variable linecolors, i.e. invisible (fully-transparent) lines, when you switch from the outer curve to the inner curve. This should be fine unless you want to create a SVG or DXF and use the graph as pattern for a cutter.
Prerequisites:
outer and inner curves must be closed (first point = last point)
you have to make sure that outer and inner curves have opposite directions (CW=clockwise and CCW=counterclockwise), this was the case in your example. Otherwise the area will not be hollow but filled.
there should be no empty line between inner and outer curves, but two empty lines between the shapes.
You can easily tell gnuplot when the outer curve ends: when the first x,y-coordinates appears again. It doesn't matter where the inner curve starts as long as the direction is reversed to the outer one.
Just for illustration, I plotted sin(x) and made the 1st structure opaque and 2nd and 3rd structure in semitransparent color.
Script: (works for gnuplot>=5.0.3)
### plot areas with holes
reset session
$Data <<EOD
0 -2 0 # outer CW
-2 0 0
0 2 0
2 0 0
0 -2 0
-0.5 0.5 1 # inner CCW
-0.5 -0.5 1
0.5 -0.5 1
0.5 0.5 1
-0.5 0.5 1
-0.5 -1 0 # outer CCW
-0.1 -0.1 0
-1 0.5 0
-1.5 -1 0
-0.5 -1 0
-0.8 0.2 1 # inner CW
-0.2 -0.1 1
-0.6 -0.8 1
-1.2 -0.8 1
-0.8 0.2 1
0 -1 0 # outer CCW
1 -1 0
1.3 0 0
0.3 0 0
0 -1 0
1.1 -0.2 1 # inner CW
0.9 -0.8 1
0.2 -0.8 1
0.4 -0.2 1
1.1 -0.2 1
EOD
myColors = "0x00ff00 0x770000ff 0x77ff0000"
myColor(i) = i+1>words(myColors) ? 0x000000 : int(word(myColors,i+1))
myColorX(i) = (x0=x1, x1=$1, y0=y1, y1=$2, \
$0==0 ? (fx=x1,fy=y1) : x1==fx && y1==fy ? last=1 : 0, \
last ? 0xff123456 : myColor(i))
set key noautotitle
set multiplot layout 1,2
set title "fixed linecolor"
plot 2*sin(2*x) lw 2, \
for [i=0:2] $Data u 1:2:(myColor(i)) index i w filledcurves lc rgb var lw 2
set title "variable line color with fully transparent lines"
plot 2*sin(2*x) lw 2, \
for [i=0:2] x1=y1=(last=0,NaN) $Data u 1:2:(myColorX(i)) index i \
w filledcurves lc rgb var lw 2
unset multiplot
### end of script
Result:

gnuplot: 3d scatter plot with circles

I am trying to do a 3d plot, where I want each point to be with my choice of color/shape/shade. The fact is that I want to use the colour palettes from here.
Lets say my data is like this --
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
and my gnuplot command looks like this --
set style fill transparent solid 0.75 noborder
set style circle radius screen 0.01
splot "data.out" with circles linecolor rgb "blue"
and I am getting this plot --
as you can see, there is no circle, every point is +.
How do I draw with circles ?
To draw with circles you need
splot "data.out" linecolor "blue" pointtype 6
To get circle try type 6 or 7. Size of circle can be changed by adding option pointsize 2 (number is value of size)

GNUplot surface using a predefined color map

My data file is a 9800x128 matrix of floating point values, and I'm having trouble plotting a surface graph, that should look similar to MATLABs surf() plot.
Using:
splot '/directory/data.txt' every ::1:1 matrix with lines
works fine, but everything is in one color which makes it impossible to see what's going on. The color palette that I've imported is:
set palette defined (0 0 0 0.5, 1 0 0 1, 2 0 0.5 1, 3 0 1 1, 4 0.5 1 0.5, 5 1 1 0, 6 1 0.5 0, 7 1 0 0, 8 0.5 0 0)
Which is similar to the default one used in MATLAB. Drawing just a 2D contour using this palette:
plot '/directory/data.txt' matrix notitle with image
works just fine as well, it's as soon as I try to marry the color map with a surface plots, as follows:
splot '/directory/data.txt' every ::1:1 matrix with image
I get the following warning message and I'm left with an empty plot.
warning: Number of pixels cannot be factored into integers matching grid. N = 1244473 K = 762
If your data is saved as matrix format, i.e. arranged as
z00 z10 z20 z30 ...
z01 z11 z21 z31 ...
z02 z12 z22 z32 ...
z03 z13 z23 z33 ...
...
then you can plot you data with
set palette defined (0 0 0 0.5, 1 0 0 1, 2 0 0.5 1, 3 0 1 1, 4 0.5 1 0.5, 5 1 1 0, 6 1 0.5 0, 7 1 0 0, 8 0.5 0 0)
splot 'data.txt' matrix with pm3d

gnuplot | 3D layers

I have the below data file which has:
1st column is the layer number.
2nd column is the X axis.
3rd column is the Y axis.
1 1999-01-19 21 0 1
1 2009-07-01 0 1 1
1 2008-08-20 2 1 1
1 2008-12-18 1 1 1
2 2004-05-12 4 1 1
2 2009-07-29 2 1 1
3 2008-08-07 0 1 1
4 2006-03-08 1 1 1
4 2004-08-31 9 1 1
4 2001-03-27 12 1 1
My questions:
1. How can I plot the above data file in 3D knowing that each layer must have different Z offset and different color?
the below must be plotted with Z=1
1 1999-01-19 21 0 1
1 2009-07-01 0 1 1
1 2008-08-20 2 1 1
1 2008-12-18 1 1 1
and the below with Z=2
2 2004-05-12 4 1 1
2 2009-07-29 2 1 1
and so on.
2.If I want to select the layer number 2, other layers must be shaded with gray and this layer must be colored with red for example, is that possible? so it's like highlighting the selected layer.
thx.
To plot the points just use
set xdata time
set timefmt '%Y-%m-%d'
set format x '%Y'
splot 'data.dat' using 2:3:1
That uses the layer number as z-value. To get something else, just specify a function for the z-value depending on the layer number:
zpos(z) = 1 + 0.5*z
splot 'data.dat' using 2:3:(zpos($1))
For the coloring use linecolor rgb variable. That allows you to specify the color in the last column. This color must be the integer representation of an rgb-tuple which is 65536*red + 256*green + blue, with red, green and blue being in the range [0:255].
The following script plots the points in layer 2 in dark red:
set xdata time
set timefmt '%Y-%m-%d'
set format x '%Y'
rgb(r,g,b) = 65536*r + 256*g + b
gray = rgb(200,200,200)
red = rgb(200,0,0)
layer = 2
set view 66,20
splot 'data.dat' using 2:3:1:($1 == layer ? red : gray) with points pt 7 linecolor rgb variable notitle
The result with 4.6.4 is:

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