Extrapolación espacial de los datos de lluvia

La consulta en Postgis es asi

drop view if exists test; create view test as select yr,ms,sum prec,st_X(geom) x,st_y(geom) y from (select station,yr,ms,sum(prec) from (select station,extract(year from fecha) yr,extract(month from fecha) ms,prec from cna.prec) ss group by yr,ms,station) s, cna.coordinates c where c.station=s.station order by yr,ms,c.station;

rm(list = ls())
library("kriging")
library(RODBC)
con <- odbcConnect("clima")
d <- sqlQuery(con, "select * from test")
str(d)

## 'data.frame':    85018 obs. of  5 variables:
##  $ yr  : int  1922 1922 1922 1922 1922 1922 1922 1922 1922 1922 ...
##  $ ms  : int  1 2 2 3 3 4 4 5 5 6 ...
##  $ prec: num  0 0 0 10.1 0 9.5 1.9 31.8 13.2 43.8 ...
##  $ x   : num  -93.1 -92.1 -93.1 -92.1 -93.1 ...
##  $ y   : num  16.8 16.9 16.8 16.9 16.8 ...

library(maps)
library(mapdata)

for (i in 2000:2010) {
    for (n in 1:12) {
        dd <- d[d$yr == i & d$ms == n, ]
        kriged <- kriging(dd$x, dd$y, dd$prec, pixels = 30)
        image(kriged, xlim = extendrange(dd$x), ylim = extendrange(dd$y), main = paste(i, 
            n), col = terrain.colors(100)[100:1])
        points(dd$x, dd$y)
        map(add = T)
    }
}

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Luego lo que hay que hacer es extraer grupos de punto para tener una serie de tiempo robusto.