I want to visualize a graph in 3d in paraview. This requires me to have points and edges connecting the points. I know how to make the points but can't seem to figure out how to make the edges.
Currently I can make .vtp files with points and associated vectors. I want to know how to modify my .vtp files to include these edges as well.
Thanks for any help!
You should use a vtkLineSource:
vtkSmartPointer<vtkLineSource> lineSource =
vtkSmartPointer<vtkLineSource>::New();
lineSource->SetPoint1(p0);
lineSource->SetPoint2(p1);
lineSource->Update();
lineSource->GetOutput() will give you a polydata that you can then write with a vtkXMLPolyDataWriter. See a full example here: http://www.vtk.org/Wiki/VTK/Examples/Cxx/GeometricObjects/Line
Related
I am trying to remove the grids on my map. I used several commands for example: plt.grid(), plt.rcParams["axes.grid"] = False but nothing happens, the map produced as is with the grids. Is there any possible way to remove the grids?
Another thing also, how can I make my plot to be smoothed instead of having the data as blocks (see below a sample of the plot).
enter image description here
Please assist in this regard.
Truly appreciate your time.
Thank you.
I'm clearly struggling with this problem for a day now and can't seem to find a nice solution to it. I would really appreciate some help and I'm really a novice in R (since last week).
Problem 1:
I have a set CSV representing grid points which I can parse into a data frame (pointname, latitude, longitude).
Eg:
name,latitude,longitude
x0y0,35.9767,-122.605
x1y0,35.9767,-122.594
x2y0,35.9767,-122.583
x0y1,35.9857,-122.605
x1y1,35.9857,-122.594
x2y1,35.9857,-122.583
x0y2,35.9947,-122.605
x1y2,35.9947,-122.594
x2y2,35.9947,-122.583
The points in this file represent the lower left corner and are arranged in row major format, meaning lowest horizontal grid points first. Each point is a certain great circle distance away from its neighbors (1km). I want to create a grid overlay on a map which I've plotted using ggmap.
What I've tried or considered:
map.grid() - this is really not useful to me as I'm not looking for any kind of projection.
geom_vline() and geom_hline(). These look good but I don't have constant x and y intercepts on a plane. Moreover, once I create a grid, I'd like to use the grid to color against a density.
geom_rect() and geom_tile(). These look really promising and may be what I want. But I'm not able to find a good way of working with these.
I'd like to fill these grid boxes later with another parameter. Any suggestions on how I can create such a grid? This may be a trivial question but I don't know a lot of R yet.
Problem 2:
How can I store or hold such a grid so that I given a point (lat,lon), I can quickly get to that grid. In fact my whole back end is in C++ and can directly output the grid name x<n>y<n> directly against a given search point. I somehow am finding it difficult to count such points against grid points so that I can fill grid with a representative color.
I'm not sure if everything of what I'm saying is clear. Please tell me if I've to clarify something.
Also note that I've Googled quite a lot and not found relevant answers although some looked close.
Eg: This, ThisToo
Thanks for the help!
This seems like a straightforward problem, yet I can't find a solution. In Sage, I've got about 30 sorted points for a scatter_plot, and I want to add the order position as a label. I know this is easy if I were working with a graph object, since I could use the vertex_labels option in plot. Is there a simple fix to get this to work for a scatter_plot, or would I need to do something like make the points vertices and keep track of the exact location of each point
Currently, you may have to use matplotlib directly or mess around with that method inside of Sage to get this. See here or here for some related questions.
I've opened Trac 20583 for this.
I have a scanned map from which i would like to extract the data into form of Long Lat and the corresponding value. Can anyone please tell me about how i can extract the data from the map. Is there any packages in R that would enable me to extract data from the scanned map. Unfortunately, i cannot find the person who made this map.
Thanks you very much for your time and help.
Take a look at OCR. I doubt you'll find anything for R, since R is primarily a statistical programming language.
You're better off with something like opencv
Once you find the appropriate OCR package, you will need to identify the x and y positions of your characters which you can then use to classify them as being on the x or y axis of your map.
This is not trivial, but good luck
Try this:
Read in the image file using the raster package
Use the locator() function to click on all the lat-long intersection points.
Use the locator data plus the lat-long data to create a table of lat-long to raster x-y coordinates
Fit a radial (x,y)->(r,theta) transformation to the data. You'll be assuming the projected latitude lines are circular which they seem to be very close to but not exact from some overlaying I tried earlier.
To sample from your image at a lat-long point, invert the transformation.
The next hard problem is trying to get from an image sample to the value of the thing being mapped. Maybe take a 5x5 grid of pixels and average, leaving out any gray pixels. Its even harder than that because some of the colours look like they are made from combining pixels of two different colours to make a new shade. Is this the best image you have?
I'm wondering what top-secret information has been blanked out from the top left corner. If it did say what the projection was that would help enormously.
Note you may be able to do a lot of the process online with mapwarper:
http://mapwarper.net
but I'm not sure if it can handle your map's projection.
I´m working with different graph algorithms, and for testing, and see the results, i need to visualize the graph.
I´m trying to use graphviz for visualization, but i dont want to use any Layout Engine, just use the real coordinates of the points.
For example: some TSPLIB instances have coordinates like: 1.54400e+04 8.88800e+03
Is this posible? should i use another tool?
Thanks in advance !
Define the nodes like
nodename [pos="2,4!"];
to position them at (x=2|y=4) (the unit is inches).
Try GoogleCharts
http://code.google.com/apis/chart/