update.earth {earth}R Documentation

Update an "earth" model

Description

Update an earth model.

Usage

## S3 method for class 'earth':
update(object = stop("no 'object' arg"),
       formula. = NULL, ponly = FALSE, ..., evaluate = TRUE)

Arguments

object The earth object
formula. The formula. argument is treated like earth's formula argument.
ponly Force pruning only, no forward pass. Default is FALSE, meaning update.earth decides automatically if a forward pass is needed. See note below.
... Arguments passed on to earth.
evaluate If TRUE (default) evaluate the new call, else return the call. Mostly for compatibility with the generic update.

Value

The value is the same as that returned by earth. If object is the only parameter then no changes are made — the returned value will be the same as the original object.

Note

If only the following arguments are used, a forward pass is unnecessary, and update.earth will perform only the pruning pass. This is usually much faster for large models.

     object
     glm
     trace
     nprune
     pmethod
     Get.crit
     Eval.model.subsets
     Print.pruning.pass
     Force.xtx.prune
     Use.beta.cache
This automatic determination to do a forward pass can be overridden with the ponly argument. If ponly=TRUE the forward pass will be skipped and only the pruning pass will be executed. This is useful for doing a pruning pass with new data, typically with penalty=0. A similar use of ponly=TRUE is to do subset selection with a different penalty from that used to build the original model. With trace=1, update.earth will tell you if earth's forward pass was skipped.

If you used keepxy=TRUE in your original call to earth, then update.earth will use the saved values of x, y, etc., unless you specify otherwise by arguments to update.earth. It can be helpful to set trace=1 to see which x, etc. update.earth uses.

See Also

earth

Examples

data(ozone1)
(a <- earth(O3 ~ ., data = ozone1, degree = 2))

# yields:
#    Selected 11 of 21 terms, and 8 of 9 predictors
#    Estimated importance: temp humidity ibt doy dpg ibh vis wind
#    Number of terms at each degree of interaction: 1 5 5
#    GCV 13.4    RSS 3762    GRSq 0.791    RSq 0.822

update(a, formula = O3 ~ . - temp) # requires forward pass and pruning

# yields:
#    Selected 15 of 21 terms, and 8 of 8 predictors
#    Estimated importance: ibt humidity doy vh ibh dpg wind vis
#    Number of terms at each degree of interaction: 1 5 9
#    GCV 13.1    RSS 3443    GRSq 0.796    RSq 0.837

update(a, nprune = 8)              # requires only pruning

# yields:
#    Selected 8 of 21 terms, and 6 of 9 predictors
#    Estimated importance: temp humidity ibt doy dpg vis
#    Number of terms at each degree of interaction: 1 5 2
#    GCV 15.1    RSS 4434    GRSq 0.766    RSq 0.79

update(a, penalty=1, ponly=TRUE)   # pruning pass only with a new penalty

# yields:
#    Selected 13 of 21 terms, and 8 of 9 predictors
#    Estimated importance: temp humidity ibt doy dpg ibh vis wind
#    Number of terms at each degree of interaction: 1 5 7
#    GCV 12.5    RSS 3675    GRSq 0.805    RSq 0.826

[Package earth version 2.3-2 Index]