On Mar 21, 2013, at 4:40 PM, Waichler, Scott R wrote: > I have a 3D field of a scalar variable (x, y, z, value). Is there a way to > generate a vector field from this data--gradient at defined points? I found > the rasterVis package for 2D data, but as yet nothing for 3D data.
Can't you just think of 'value' as a "potential" and then differentiate (using sweep?) along the three principal axes to construct the partial derivatives (eg. diff(value)/diff(x) at constant y and z) which would then form the components of the vector field? That's how one goes from gravitational or electrical potential to the corresponding vector fields. E <- grad(V), As always: Data would help clarify. -- David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
