I'm trying to graph an approximate solution (finite element method) to the Navier-Stokes equation. I've got a file called plotNSu1 that looks like this:
6 1 4.21022e-34
5.95 1 8.15227e-34
5.9693 0.970854 0.055197
6 1 4.21022e-34
5.9693 0.970854 0.055197
6 0.95 0.0941333
6 1 4.21022e-34
5.9693 0.970854 0.055197
5.92625 0.951192 0.0915468
5.9693 0.970854 0.055197
5.95 1 8.15227e-34
5.92625 0.951192 0.0915468
...
(The entries are x y z, grouped so that there's a blank line between each set of 4 points).
I use the following command to plot:
splot "plotNSu1" with lines
Butt I would like to make it look nicer, easier to read. (There's a small dip at one spot that's difficult to see, but is an important part of the solution).
I've found lots of examples using pm3d interpolate, but none seem to work for me. I've tried set style pm3d, and other set style commands, I've tried set pm3d map interpolate 10,10, and splot "plotNSu1" with pm3d, as well as so many other similar things stolen from the examples I've found that I can't keep track. Most of the time I just get an empty window with the color key and no plot, and often it sends me an empty 2d window.
I would like to have the color change with the contour of the plot, to make the little dip easier to see. Does anyone know how to do this? Here's one of the websites I've been trying to use, to see what I'm aiming for: http://gnuplot.sourceforge.net/demo/pm3d.html
I tried to post the image, but as I do not have enough reputation, I can't. But it's difficult to see what's going on because the graph is just all red.
I found a way to make this work, more or less, thanks to #Christoph's help and this other question suggested by stackoverflow: gnuplot pm3d plot triangle data
With my data in the file described above, in gnuplot I type:
set dgrid3d
set pm3d corners2color c2
splot "plotNSu1" using 1:2:3 with pm3d
The result isn't perfect, it looks a little choppy, but it basically does what I wanted, I can see the "dip" in my graph much better now.
Related
I have data generated from python code as such:
u, v = np.mgrid[0:2*np.pi:180*1j, 0:np.pi:90*1j]
X = np.cos(u)*np.sin(v)
Y = np.sin(u)*np.sin(v)
Z = np.cos(v)
This is written to a file tmp.dat, and I attempt to plot it in gnuplot with:
set pm3d
set palette
set hidden
splot "tmp.dat" using 1:2:3 with pm3d
However, this gives me:
It's in the general vicinity of what I want, but I'd like a smooth sphere as opposed to this. (My real data is in the same vein; with an enclosed surface I want to have transparency on.) I've tried adding set dgrid3d 50,50 to try and interpolate, however, I don't actually understand what I'm getting from this:
Any help or advice would be enormously appreciated. Changing the data to parametric (with u and v sweep data) is an option, however, I'm not certain how to do that - when I tried, the result was the same.
Not a complete answer, but part of your problem is that "set hidden3d" is not usable here. Gnuplot has two separate subsystems for representing surfaces. One of them, controlled by "set hidden3d", tracks bounding line segments and can remove occluded portions. The other is pm3d, which uses solid-fill quadrangles rather than bounding line segments. pm3d plots do not have the option of removing occluded quadrangles, but you can get a similar effect by depth-sorting them. The relevant command is
set pm3d depthorder
This works reasonably well if the individual quadrangles are approximately square but it gives bad results for long thin quadrangles, since the two ends of the facet can have conflicting depths with regard to neighboring facets.
This is my second question today, I thought about editing the other one with this info but the problems doesn't seem to be related... So, with this data file, and using this code:
set terminal qt
s=101
set size square
set palette rgb 34,35,36;
set zrange[-1.8e-5:1.8e-5]
set pm3d at sb
set autoscale fix
do for [i=0:0]{
splot 'itp.txt' u 1:2:3 every:::(i*s)::(s+i*s) notitle w pm3d
}
I get this black image. This is clearly not working properly... but if I slide my finger through my notebook's touchpad while in the qt's output interactive window, this image pops up, which is what I wanted. It seems to work everywhere, except when the graph fit the "canvas". Example 1 & example 2. I'm not even sure what sliding my fingers through the touchpad while on qt's output window does, but it seems to be fixing something. So what should I do? Thank you in advance!
*qt is the qt terminal in gnuplot
Looking at the two figures you posted, it seems that the effect has to do with a changing xrange. I copied your datafile and script, and adding:
set xrange[-200:300]
did the trick for me. Also, you may consider fixing (if at all possible) your color bar range, by adding:
set cbrange[xx:xx]
with your data, I tried:
set cbrange[0:1.8e-8]
and the result looks completely different. Hope this helps.
I have a file with scattered data (points located approximatelly on the vertices of a regular grid): first two columns are the x and y coordinates, then a few more columns with other data that I need to plot. I want to obtain color maps that represent this data, and since points are scattered I'm using dgrid3d to generate a regular grid and have a smoother representation. My problem is that when I set dgrid3d, gnuplot ignores the x and y ranges and plot the grid outside the figure frame. Bellow is a minimal script to reproduce my problem:
set view map
set yrange [0.4:0.8]
set xrange [0.2:0.8]
set pm3d
set style data lines
set dgrid3d 100,100,4
splot "./Terr.dat" using 1:2:(log($6)) pal
The result that I obtain is the following image:
Setting the option clip1in or clip4in of pm3d has no effect. If I unset view so that the result is a 3D surface, it also ignores the x and y ranges. I could easily write an script to pre-process the data and remove the points outside the range I want, but gnuplot should be able to manage this. Any idea?
I'm using gnuplot 4.2 patchlevel 6
Thanks!
I'm not sure that I am able to reproduce your problem, but there are a few funny things with your script. I'm not exactly sure what the line set style data lines is supposed to do in this context as you're plotting with pm3d. I created a simple datafile:
0 1 4
1 0 5
0 0 2
1 1 3
And I plotted it using this script:
set view map
set yrange [0.4:0.8]
set xrange [0.2:0.8]
set dgrid3d 100,100,4
splot 'test.dat' u 1:2:3 w pm3d
And it seemed to "work" (I'm using gnuplot 4.6.0).
There are a few things of note however -- Notice that every point in my original domain was out of the given x and y ranges. Gnuplot still used those points when constructing the surface. This is also demonstrates reasonably nicely what the gnuplot weighting function looks like (although we could do even better by using only 1 point in our data file.)
UPDATE
Between my 2 computers, I have access to gnuplot4.2.6, gnuplot4.3.0, gnuplot4.4.2, gnuplot4.6.0, gnuplot4.6.1 and gnuplot4.7.0. gnuplot4.2.6 is the only version which exhibits the behavior you describe. It looks to me like they changed the behavior of pm3d in the 4.3 CVS branch, but didn't push those changes back into gnuplot4.2. The easy fix is to upgrade to gnuplot4.6 -- I've been using it as my default gnuplot for a few months now and it seems to be pretty stable.
Using gnuplot 4.6 patchlevel 1, with the following commands,
set grid linewidth 1 linecolor rgb"#888888"
set datafile separator ","
plot for [n=2:100] "data.csv" using 1:(column(n)) with lines linewidth 2
and the following example data in the file "data.csv",
time,S1,S2
0,0.00015,0
0.1,0.0001357256127053939,1.427438729460607e-005
0.2,0.0001228096129616973,2.719038703830272e-005
0.3,0.0001111227331022577,3.887726689774233e-005
0.4,0.0001005480069053459,4.945199309465411e-005
0.5,9.097959895689501e-005,5.902040104310499e-005
0.6,8.232174541410396e-005,6.767825458589604e-005
0.7,7.448779556871142e-005,7.551220443128858e-005
0.8,6.739934461758323e-005,8.260065538241677e-005
0.9,6.098544896108986e-005,8.901455103891014e-005
1,5.518191617571635e-005,9.481808382428365e-005
the resulting plot looks this:
Question: why does the grid only extend partway from the bottom, and not cover the whole plot? I tried a considerable amount of experimentation with the set xtics and ytics commands, arguments to grid, and more, and have not been able to get the grid to cover the whole plot. What am I missing?
Great question! In fact, the answer is that the grid does cover the whole plot. The problem is that the key is taking over. Try it again, but with an unset key in there before your plot command.
What's happening is that gnuplot is reserving space in the key for all of the columns which have no data. Nothing gets put in the space that was reserved since no reasonable data was found. Ultimately, this pushes the 2 lines that were visible out of the viewable canvas area as well.
I've reproduced this using the x11, png, postscript and pngcairo terminals.
Note that this behavior seems to be version dependent:
With gnuplot 4.4.2 (OS-X, png terminal)
With gnuplot 4.6.0 (OS-X, png terminal)
For those using gnuplot 4.4.4, perhaps there was a bug fix which made it work for gnuplot 4.4.4 and then a regression. It seems to persist into gnuplot 4.7.0 as well. I might file a bug report.
I am using Gnuplot to successfully plot some time series data. However, the series are fairly dense (10,000's of samples in about 5 inches of space), and when I plot multiple series, it is hard to see underneath the series that was plotted on top. Is there any way to make the lines have a bit of opacity or transparency (i.e. make the line transparent so underneath lines are visible)?
Excel has this capability, but I would much prefer to use Gnuplot.
Below is a sample of what I'm talking about. You can't see the red lines under the green lines. I would actually like to add a third time series. I am plotting with the command:
plot [][-3:3] 'samples_all.csv' using 1:7 title 'horizontal' w l ls 1, '' using 1:8 title 'vertical' w l ls 2"
Good news! This has been implemented in gnuplot. Example syntax is
plot x lw 10, -x lw 10 lc rgb "#77000000"
This will plot x as a red line and -x as a transparent black line (it looks gray). The first pair of two characters in the rgb specification define the alpha (transparency) channel ("#AARRGGBB"). The normal syntax ("#RRGGBB") still works.
old (gnuplot < 5.0 or so) answer for reference:
If you want to make lines plotted for time series data, the answer is no (see discussion here). You can't set a line style to be transparent. Transparency only works for filling under curves, and it has to be printed to the right terminal type.
I ran into this problem myself recently, I hope this feature will be added in a future version of gnuplot.
This may be what you're looking for.