construct.blocks.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/blocks.R
\name{construct.blocks}
\alias{construct.blocks}
\title{Construct blocks from \code{formulas} and \code{predictorMatrix}}
\usage{
construct.blocks(formulas = NULL, predictorMatrix = NULL)
}
\arguments{
\item{formulas}{A named list of formula's, or expressions that
can be converted into formula's by \code{as.formula}. List elements
correspond to blocks. The block to which the list element applies is
identified by its name, so list names must correspond to block names.
The \code{formulas} argument is an alternative to the
\code{predictorMatrix} argument that allows for more flexibility in
specifying imputation models, e.g., for specifying interaction terms.}

\item{predictorMatrix}{A numeric matrix of \code{length(blocks)} rows
and \code{ncol(data)} columns, containing 0/1 data specifying
the set of predictors to be used for each target column.
Each row corresponds to a variable block, i.e., a set of variables
to be imputed. A value of \code{1} means that the column
variable is used as a predictor for the target block (in the rows).
By default, the \code{predictorMatrix} is a square matrix of \code{ncol(data)}
rows and columns with all 1's, except for the diagonal.
Note: For two-level imputation models (which have \code{"2l"} in their names)
other codes (e.g, \code{2} or \code{-2}) are also allowed.}
}
\value{
A \code{blocks} object.
}
\description{
This helper function attempts to find blocks of variables in the
specification of the \code{formulas} and/or \code{predictorMatrix}
objects. Blocks specified by \code{formulas} may consist of
multiple variables. Blocks specified by \code{predictorMatrix} are
assumed to consist of single variables. Any duplicates in names are
removed, and the formula specification is preferred.
\code{predictorMatrix} and \code{formulas}. When both arguments
specify models for the same block, the model for the
\code{predictMatrix} is removed, and priority is given to the
specification given in \code{formulas}.
}
\examples{
form <- list(bmi + hyp ~ chl + age, chl ~ bmi)
pred <- make.predictorMatrix(nhanes[, c("age", "chl")])
construct.blocks(formulas = form, pred = pred)
}
\seealso{
\code{\link{make.blocks}}, \code{\link{name.blocks}}
}