| choose.trans {MethComp} | R Documentation |
Choose a function and inverse based on a text string; check whether two functions actually are each others inverse.
choose.trans( tr ) check.trans( trans, y, trans.tol = 1e-05 )
tr |
A character string, or a list of two functions, each others inverse. |
trans |
A list of two functions, each other's inverse. |
y |
Vector of numerical values where the functions should be each other's inverse. |
trans.tol |
Numerical constant indication how precise the evaulation should be. |
choose.trans returns a list with two elements, both functions which
are each other's inverse. This is intended to be stored
as an attribute "Transform" with the resulting object
and used in plotting and reporting. All results will be on
the transformed scale. Can also be a character constant, in
which case the appropriate list will be generated.
Possibilities are: "exp", "log", "logit", "pctlogit"
(transforms percentages by the logit), "sqrt", "sq" (square),
"cll" (complementary log-minus-log), "ll" (log-minus-log).
If there is no match NULL is returned, which will correspond to no
transformation.
check.trans returns nothing.
Bendix Carstensen, Steno Diabetes Center, http://www.biostat.ku.dk/~bxc.
choose.trans( "logit" )