| builtin.gams {UCS} | R Documentation |
List available GAMs (generalised association measures) that can
be computed with functions such as gam.score, add.gams
and gam.iso, or test whether a specific GAM is available.
Additional GAMs can be defined with the register.gam function.
builtin.gams() is.builtin.gam(names) register.gam(name, equation, iso.equation=NULL)
names |
a character vector specifying the names of GAMs whose availability is tested |
name |
a single character string specifying the name of a GAM that is defined or re-defined |
equation |
a function that computes GAM scores from standard or ebo-coordinates (see below for details) |
iso.equation |
an optional function that computes iso-surfaces in standard or ebo-coordinates (see below for details) |
The names of built-in GAMs are identical to those of the corresponding
standard AMs (e.g. t.score and chi.squared.corr).
The equation argument of register.gam, i.e. the equation
defining a new GAM), must be a function with the signature (o,
e, b, f, f1, f2, N). This function can computes GAM scores either
from the ebo-coordinates e, b, o or from the standard
coordinates f, f1, f2, N. It is always invoked with all seven
arguments, which are guaranteed to be vectors of the same length, and
must return a vector of corresponding GAM scores.
When an explicit equation for iso-surfaces \{g = γ\}
exists, it can be made available through the optional argument
iso.equation, which expects a function with the signature
(gamma, e, b, f1, f2, N). Again, all six arguments are
guaranteed to be vectors of the same length, and the function must
return the corresponding o (or f) coordinates that
satisfy the condition g(o, e, b) = γ (or g(f, f_1,
f_2, N) = γ). When the iso.equation function is
available for a GAM, it will be used by gam.iso for greater
speed and accuracy. Otherwise, the iso surface is determined by
a binary search algorithm (which has a unique solution for any
semi-sound GAM).
The signatures of the equation and iso.equation
functions are checked by register.gam, which will abort with an
error message if they are not correct.
builtin.gams returns a character vector listing the names of
available GAMs. is.builtin.gam returns a logical vector
indicating which of the GAMs in the vector names are available.
builtin.ams, gam.score,
add.gams, gam.iso, gam.helpers
print(builtin.gams())
all(is.builtin.gam(c("MI", "t.score", "chi.squared")))
register.gam("MI5",
eq = function (o, e, b, f, f1, f2, N) { log10(o^5 / e) },
iso = function (gamma, e, b, f1, f2, N) { 10^(gamma/5) * e^(1/5) })