generateGridDesign: Generates a grid design for a parameter set.

In ParamHelpers: Helpers for Parameters in Black-Box Optimization, Tuning and Machine Learning

Generates a grid design for a parameter set.

Description

The following types of columns are created:

numeric(vector)	numeric
integer(vector)	integer
discrete(vector)	factor (names of values = levels)
logical(vector)	logical

If you want to convert these, look at BBmisc::convertDataFrameCols(). Dependent parameters whose constraints are unsatisfied generate NA entries in their respective columns. For discrete vectors the levels and their order will be preserved.

The algorithm currently performs these steps:

1. We create a grid. For numerics and integers we use the specified resolution. For discretes all values will be taken.

2. Forbidden points are removed.

3. Parameters are trafoed (potentially, depending on the setting of argument trafo); dependent parameters whose constraints are unsatisfied are set to NA entries.

4. Duplicated points are removed. Duplicated points are not generated in a grid design, but the way parameter dependencies are handled make this possible.

Note that if you have trafos attached to your params, the complete creation of the design (except for the detection of invalid parameters w.r.t to their requires setting) takes place on the UNTRANSFORMED scale. So this function creates a regular grid over the param space on the UNTRANSFORMED scale, but not necessarily the transformed scale.

generateDesign will NOT work if there are dependencies over multiple levels of parameters and the dependency is only given with respect to the “previous” parameter. A current workaround is to state all dependencies on all parameters involved. (We are working on it.)

Usage

generateGridDesign(par.set, resolution, trafo = FALSE)

Arguments

par.set	ParamSet Parameter set.
resolution	(integer) Resolution of the grid for each numeric/integer parameter in par.set. For vector parameters, it is the resolution per dimension. Either pass one resolution for all parameters, or a named vector.
trafo	(logical(1)) Transform all parameters by using theirs respective transformation functions. Default is FALSE.

Value

data.frame. Columns are named by the ids of the parameters. If the par.set argument contains a vector parameter, its corresponding column names in the design are the parameter id concatenated with 1 to dimension of the vector. The result will have an logical(1) attribute “trafo”, which is set to the value of argument trafo.

Examples

ps = makeParamSet(
  makeNumericParam("x1", lower = -2, upper = 1),
  makeNumericParam("x2", lower = -2, upper = 2, trafo = function(x) x^2)
)
generateGridDesign(ps, resolution = c(x1 = 4, x2 = 5), trafo = TRUE)

ParamHelpers documentation built on July 4, 2022, 5:07 p.m.