gam.scope | R Documentation |
Given a data.frame as an argument, generate a scope list for use in step.Gam, each element of which gives the candidates for that term.
gam.scope(frame, response = 1, smoother = "s", arg = NULL, form = TRUE)
frame |
a data.frame to be used in |
response |
The column in |
smoother |
which smoother to use for the nonlinear terms; i.e. "s" or "lo", or any other supplied smoother. Default is "s". |
arg |
a character (vector), which is the argument to |
form |
if |
This function creates a similar scope formula for each variable in the
frame. A column named "x" by default will generate a scope term
~1+x+s(x)
. With arg=c("df=4","df=6")
we get
~1+x+s(x,df=4)+s(x,df=6)
. With form=FALSE, we would get the character
vector c("1","x","s(x,df=4)","s(x,df=6")
.
a scope list is returned, with either a formula or a character vector for each term, which describes the candidates for that term in the Gam.
Written by Trevor Hastie, following closely the design in the
"Generalized Additive Models" chapter (Hastie, 1992) in Chambers and Hastie
(1992). This version of gam.scope
is adapted from the S version.
Hastie, T. J. (1991) Generalized additive models. Chapter 7 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.
step.Gam
data(gam.data) gdata=gam.data[,1:3] gam.scope(gdata,2) gam.scope(gdata,2,arg="df=5") gam.scope(gdata,2,arg="df=5",form=FALSE) gam.scope(gdata,2,arg=c("df=4","df=6"))
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