earth (version 2.3-0)

format.earth: Format "earth" objects

Description

Return a string representing an earth expression.

Usage

## S3 method for class 'earth':
format(x = stop("no 'x' arg"),
       digits = getOption("digits"), use.names = TRUE,
       decomp = "anova",  style = "h", colon.char = ":", ...)

Arguments

x

An earth object. This is the only required argument.

digits

Number of significant digits. The default is getOption(digits).

use.names

If TRUE (default), use variable names. Else use names of the form x[,1].

decomp

One of "anova" (default) order the terms using the "anova decomposition", i.e., in increasing order of interaction "none" order the terms as created during the earth forward pass.

style

Formatting style. One of "h" (default) more compact "pmax" for those who prefer it and for compatibility with old versions of earth "bf" basis function format.

colon.char

Change colons in the returned string to colon.char. Default is ":", i.e., no change. Specifying colon.char="*" can be useful in some contexts to change names of the form x1:x2 to x1*x2.

...

Unused, but provided for generic/method consistency.

Value

• A character representation of the earth object.

  If there are multiple responses, format.earth will return multiple strings.

  If there are embedded GLM model(s), the strings for the GLM model(s) come after the strings for the standard earth model(s).

See Also

earth, pmax,

Examples

a <- earth(Volume ~ ., data = trees)
cat(format(a))

# yields:
#    23.2
#    +  5.75 * h(Girth-12.9)
#    -  2.87 * h(12.9-Girth)
#    + 0.718 * h(Height-76)

cat(format(a, style="pmax")) # default formatting style prior to earth version 1.4

# yields:
#    23.2
#    +  5.75 * pmax(0,  Girth -   12.9)
#    -  2.87 * pmax(0,   12.9 -  Girth)
#    + 0.718 * pmax(0, Height -     76)

cat(format(a, style="bf"))

# yields:
#    23.2
#    +  5.75 * bf1
#    -  2.87 * bf2
#    + 0.718 * bf3
#  
#     bf1  h(Girth-12.9)
#     bf2  h(12.9-Girth)
#     bf3  h(Height-76)