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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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Hi Kevin, > > When the user fixes an e0 value, construct a Gridded2DSet with > > manifold dimension = 1, over domain (r, e). Basically, this > > would be a set of (r, e0) for a sequence of r values. Then > > resample your FlatField ((r, e) -> (h, s)) to this Gridded2DSet, > > and display the FlatField returned by this call to resample(). > > > > The problem here is that I would like the user to choose a different e > (eX) and have it update the display. Please see the link below for an > illustration: > > http://www.cimms.ou.edu/~kmanross/VCPRPE/Examples/vcpTest.html > > I guess the more basic question I have is, is there a way for VisAD to > handle variable domains? resample() remaps the range to the existing > domain of a FlatField, but is there a way to reset/change the domain and > resample() while the program is running? Absolutely. VisAD provides lots of support for building interaction techniques. Here what you want is a CellImpl that is triggered by user input to do the resample(). There is an excellent example (in Python) at: http://www.ssec.wisc.edu/~tomw/visadtutor/t7example.html and another example in visad/examples/Simple.java, described at: http://www.ssec.wisc.edu/~billh/guide.html#2.2 Also see: http://www.geogr.uni-jena.de/~p6taug/visad/tutorial/s6/Section6.html for the Interaction section of Ugo's excellent tutorial. > > With ScalarMaps h -> YAxis and s -> XAxis, you'll get a scatter > > diagram. Given that h and s are both dependent variables with > > no simple functional dependency between them, in general this > > must be a scatter diagram rather than a line graph. If you have > > prior knowledge that there is some simple graph relation between > > them, you can extract their values from the resampled FlatField > > and construct a FlatField with MathType (h -> s) or (s -> h) > > and appropriate topology. > > > > Indeed the relationship should be a line graph (although the > relationship may not be so "simple ;-). If you have a copy of Doviak > and Zrnic handy, I am calculating equations (2.28b and c - pg. 21) and > then trying to replicate Figure 2.8 (p. 23) though with only one line at > a time based on the user's choice of e. OK. If you want a line graph you'll need to extract arrays of h and s values from your FlatField (with MathType ((r, e) -> (h, s))) via its getFloats() method, and using them to construct a Gridded2DSet with manifold dimension =1 (and with MathType Set(h, s)). > > Note in your code 'new Irregular1DSet(h, h_vals )' can be a > > Gridded1DSet as long as the h_vals array is sorted (can be > > either ascending or descending). > > > > I played around with both and found them to produce the same output. Is > the GriddedSet more efficient than the IrregularSet? Not significantly. But the Irregular1DSet constructor just sorts it samples and then constructs a Gridded1DSet (not true in 2D and 3D cases). Good luck, Bill
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