earth (version 0.1-2)

mars.to.earth: Convert a 'mars' to an 'earth' object

Description

Convert a mars object to an earth object

Usage

mars.to.earth(object)

Arguments

object
A mars object, created using mars in the mda package.

Value

  • The value is the same as that returned by earth but with skeletal versions of rssVec, gcvVec, and prune.terms. You can fully initialise these components by calling update.earth after mars.to.earth, but if you do this selected.terms may change. However with pmethod="backward" a change is unlikely --- selected.terms would change only if GCVs are so close that rounding differences have an effect.

See Also

earth, mars

Examples

Run this code
# The example is not run with example("mars.to.earth") because that would 
# require making the earth package dependent on the mda package.

library(mda)
a <- mars(trees[,-3], trees[,3])
a <- mars.to.earth(a)
summary(a, digits = 2) # the standard earth functions can now be used

# yields (note the reconstructed call):
#    Call:
#    earth(x = trees[, -3], y = trees[, 3])
#    
#    Expression:
#      20 
#      +  5.4 * pmax(0,  Girth -     12) 
#      -  2.6 * pmax(0,     12 -  Girth) 
#      + 0.72 * pmax(0, Height -     76) 
#    
#    Number of cases: 31
#    Selected 4 of 5 terms, and 2 of 2 predictors
#    Number of terms at each degree of interaction: 1 3 (additive model)
#    GCV: 13     RSS: 251     GRSq: 0.95     RSq: 0.97

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