R: Trend Modelling

Trend Modelling {RandomFields} | R Documentation

## Trend Modelling

### Description

The coding of trend, in particular multivariate trends, will be described here

### Details

See RFcalc, RMtrend and also the examples below for some insight on the possibilities of trend modelling.

### Author(s)

Martin Schlather, schlather@math.uni-mannheim.de

### See Also

RFcalc, RM, RMmodels, RMtrend, RMmodelsMultivariate

### Examples

    require(geoR)

    data(ca20) ## data set from geoR
    ca20.df <- as.data.frame(ca20)
    head(ca20.df)
    RFoptions(coordnames=c("east", "north"), varnames="data")

    ## covariance model with variance, scale and nugget to be estimated;
    ## just to abbreviate later on
    M <- RMexp(var=NA, scale=NA) + RMnugget(var=NA)

    ## short definition of a trend using the fact that ca20.df is a
    ## data.frame
    ca20.RFmod02 <- ~ 1 + altitude + M
    (ca20.fit02.RF <- RFfit(ca20.RFmod02, data=ca20.df))

    ## long definition, which allows also for more general constructions
    ca20.RFmod02 <- NA + NA*RMcovariate(ca20.df$altitude) + M
    (ca20.fit02.RF <- RFfit(ca20.RFmod02, data=ca20.df))

    ## Note that the following also works.
    ## Here, the covariance model must be the first summand
    ca20.RFmod02 <- M + NA + ca20.df$altitude
    print(ca20.fit02.RF <- RFfit(ca20.RFmod02, data=ca20.df))

    ### The following does NOT work, as R assumes (NA + ca20.df$altitude) + M
    (ca20.RFmod02 <- NA + ca20.df$altitude + M)
    try(ca20.fit02.RF <- RFfit(ca20.RFmod02, data=ca20.df)) ### error ...

    ## factors:
    ca20.RFmod03 <- ~ 1 + area + M ###
    (ca20.fit03.RF <- RFfit(ca20.RFmod03, data=ca20.df))

[Package RandomFields version 3.1.50 Index]