imptree_params: Method parameters for generating imptree objects
In imptree: Classification Trees with Imprecise Probabilities

Description Usage Arguments Details Value Author(s) See Also Examples

Initializing and validating the essential probability method specific parameters

1	imptree_params(args, method)

`args`	Named list containing the arguments to be processed. May be `NULL` for default values. See details.
`method`	Probability method as character, as supplied to `imptree`.

imptree_params() is not exported into the user's namespace.

For all methods args takes the following inputs:

s: Hyperparamter of the imprecise Dirichlet model (s >= 0), see below.
correction: Entropy correction to be carried out (Default "no"), see below.
splitmetric: Split criterion to use (Default "globalmax"), see below.

The hyperparamter s of the imprecise Dirchlet model (IDM) may be given as any non-negative value. It defines the impression the locally applied IDMs introduce. With increasing values of s more impression is added. For s=0 the IDM collapses to a precise Dirichlet model. This value is ignored for method = "NPI".

To account for a varying number of categories of the splitting candidates Strobl proposed the use of a correction based on the Miller-entropy correction: correction = "strobl". In their work Abellan and Moral favoured for the IDM the use of a generalized Hartley measure such that the final measure may be viewed as measure of total uncertainty: correction = "abellan". This correction method is not available for method = "NPI".

When deciding for split canditates a split criterion is applied. "globalmax" splits on maximal entropy of local models (with a global IDM parameter s). For "range" the splitting variable is found by taking the whole entropy interval into account. localmax is only available for IDM and split on maximal entropy, however with s dependent on the number of missing values in the class variable in the node

A list containing the sanitized and validated parameters.

Paul Fink Paul.Fink@stat.uni-muenchen.de

imptree, imptree_control

## Note: 
## The function is used internally by imptree (not exported).

## default constructed for method IDM
imptree:::imptree_params(NULL, method = "IDM")

## passing arguments as list ('s' is not required for 'NPI')
imptree:::imptree_params(args = list(correction = "strobl", 
                                     splitmetric = "globalmax"),
                         method = "NPI")