Re: [R-sig-Geo] About plotting maximum data over a region.-

[Freddy López]

Dear Ashton,

Thanks a lot for your answer.

At the moment, I partially followed your suggestion 'expanding' each year
for a expanded set of coordinates using the function krige.conv() from geoR
library. By using this, I can plot it with image() function but I'm not
sure about the utilization of kriging with maxima data.

Cheers...


On Tue, Aug 31, 2010 at 14:13, Ashton Shortridge <ash...@msu.edu> wrote:

> On 2010-08-31, Freddy López, wrote:
> > Dear ALL,
> >
> > Perhaps my problem does not belong exactly to this list... I apologize
> for
> > this.
> >
> > My situation is the following:
> >
> > I have a dataset with 26 sites (columns) whose values are annual
> > maximum since 1960 up to 1999 (40 rows) and I want to plotting it.  Of
> > course I have also the coordinates from each site.
> >
> > I have seen one example similar to what I am looking for (function
> >
> > simmaxstab() in SpatialExtremes):
> > >filled.contour(x, y, log(data[,,1]), color.palette = terrain.colors)
> >
> > But at first glance it does not work to my data. The error that it report
> is:
> > > filled.contour(coor2[,1], coor2[,2], nueva2)
> >
> > Error en filled.contour(coor2[, 1], coor2[, 2], nueva2) :
> >   increasing 'x' and 'y' values expected
> >
> > Can anybody help me to plot my particular dataset?
> >
> > Thanks in advance.
>
> Hi Freddy,
>
> Your problem is that filled.contour assumes a matrix input - essentially a
> whole field of z-values. I suspect what you have are scattered locations
> with
> z-values for each one. You have two options:
>
> 1. Interpolate your scattered points to a grid, and plot that, maybe with
> filled.contour. Interpolation methods are very numerous in R and beyond the
> scope of this answer, but maybe idw() in the gstat package would be a place
> to
> start.
>
> 2. Plot the point locations directly, and color them according to their z-
> value. Maybe something like this would work:
> par(pty="s")  # square plotting region
> plot(coor2[,1], coor2[,2], main="Locations")  # Just the locations
> plot(coor2[,1], coor2[,2], main="Nueva2 at my Locations",
>     col=rainbow(n=10, start=0.50, end=0.65)[cut(nueva2,10)], pch=19)
> points(coor2[,1], coor2[,2], pch=1, cex=1.1)  # draws a black outline
>
> Hope this helps,
>
> Ashton
>
> -----
> Ashton Shortridge
> Associate Professor                     ash...@msu.edu
> Dept of Geography                       http://www.msu.edu/~ashton
> 235 Geography Building          ph (517) 432-3561
> Michigan State University               fx (517) 432-1671
>



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