creategroups: Creating Homogeneous Groups
In biotools: Tools for Biometry and Applied Statistics in Agricultural Science

Description Usage Arguments Details Value Author(s) Examples

A function to create homogeneous groups of named objects according to an objective function evaluated at a covariate. It can be useful to design experiments which contain a fixed covariate factor.

1	creategroups(x, ngroups, sizes, fun = mean, tol = 0.01, maxit = 200)

`x`	a numeric vector of a covariate at which to evaluate the objective function.
`ngroups`	the number of groups to create.
`sizes`	a numeric vector of length equal to `ngroups` containing the group sizes.
`fun`	the objective function, i.e., to create groups with similar `fun`; default is `mean`.
`tol`	the tolerance level to define the groups as homogenenous; see details.
`maxit`	the maximum number of iterations; default is 200.

creategroups uses a tol value to evaluate the following statistic: h = ∑_{j}^{ngroups} abs( t_{j+1} - t_j ) / ngroups, where t_j = fun(group_j). If h ≤q tol, the groups are considered homogeneous.

A list of

`covar`	a character indicating the name of the covariate.
`func`	a character indicating the name of the objective function.
`val.func`	a numeric vector containing the values evaluated by `func` on each group.
`niter`	the number of iteration require to achieve convergence.
`labels`	a list containing the labels of the objects in each group.
`groups`	a list of named vectors containing the values for the groups

Anderson Rodrigo da Silva <anderson.agro@hotmail.com>

x <- rnorm(10, 1, 0.5)
names(x) <- letters[1:10]
creategroups(x, ngroups = 2, sizes = c(5, 5))
creategroups(x, ngroups = 3, sizes = c(3, 4, 3), tol = 0.05)

# End (not run)