Using gnuplot v5 patch 6 on windows 10 (wxt terminal)
I have a data file of 2D vectors arranged in six columns (x, y, v_x, v_y, v_mag, rho) that I'm trying to plot as a heatmap of v_mag against x and y. The plot generates fine, but it's always coming up with
"No dimension information for 80000 pixels total. Try 200 x 400"
But I have no idea where to specify this in the terminal.
I realise that I can use pm3d map for this, but this doesn't work without setting dgrid3d and that causes problems with plotting dots on top of the heatmap which I'm also doing. I also don't want to generate a matrix file just for the image plot since I need the vector data for analysis later.
In terms of an example, the plot will generate if I literally just write:
plot 'vectors.dat' using 1:2:5 with image, 'dots.dat' with dots
EDIT: added 'set pm3d' to example code
EDIT: example is now minimal code to produce desired plot
EDIT: example data file can be found here
Any help would be appreciated.
After updating my gnuplot to v5.2, this problem has disappeared.
Related
I have data files that have the following x, y, z structure:
-0.2385905666 -0.0131579757 -0.0000000035
-0.2385905666 -0.0114839591 -0.0000000096
-0.2385905666 -0.0098099425 -0.0000000249
-0.2385905666 -0.0081359259 -0.0000000613
-0.2385905666 -0.0064619093 -0.0000001440
I currently use gnuplot to plot the data:
splot [0:4] [0:7] "xyzData.dat" using ($1):($2):($3) with lines
The resulting plots look like this example.
I want to use Python 3.7/Matplotlib instead. I have tried various surface and contour plotting methods and keep running into a problem with my Z data. For example, I tried this:
plt.contourf(x, y, z, 100)
I get the error below and don't understand why based on similar posts here at Stackoverflow, although I'm guessing it may have something to do with a grid definition:
Input z must be a 2D array.
At any rate, I am hoping that there is a different plotting method that would be more appropriate. If anyone has a newbie-level suggestion about where to start, I would be grateful.
Update:
I came across this post:
How to do a contour plot from x,y,z coordinates in matplotlib? (plt.contourf or plt.contour)
It almost works, as shown below. However, I can't figure out how to modify the colors or contour spacing to be more similar to my gnuplot example above. If anyone knows, I would be very grateful for any hints!
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.
I wanted to get a scatter plot but the constraint is to plot these points over an image with same dimension as the range of points. Is is possible? If yes which library is good to start with? I tried using gnuplot but it is causing problems. For now I have a code which was stated here but didn't work. I tried using a bitmap image with the points to be plotted in data1.dat file and used the gnuplot script which is stated in the link
set terminal pngcairo transparent
set output 'Figure1.bmp'
plot "Co_ordinates0.dat"
set output
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.
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.