R: Construct blocks from 'formulas' and 'predictorMatrix'

construct.blocks {mice} | R Documentation

## Construct blocks from `formulas` and `predictorMatrix`

### Description

This helper function attempts to find blocks of variables in the specification of the `formulas` and/or `predictorMatrix` objects. Blocks specified by `formulas` may consist of multiple variables. Blocks specified by `predictorMatrix` are assumed to consist of single variables. Any duplicates in names are removed, and the formula specification is preferred. `predictorMatrix` and `formulas`. When both arguments specify models for the same block, the model for the `predictMatrix` is removed, and priority is given to the specification given in `formulas`.

### Usage

    construct.blocks(formulas = NULL, predictorMatrix = NULL)

### Arguments

`formulas` | A named list of formula's, or expressions that can be converted into formula's by `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 `formulas` argument is an alternative to the `predictorMatrix` argument that allows for more flexibility in specifying imputation models, e.g., for specifying interaction terms.
`predictorMatrix` | A numeric matrix of `length(blocks)` rows and `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 `1` means that the column variable is used as a predictor for the target block (in the rows). By default, the `predictorMatrix` is a square matrix of `ncol(data)` rows and columns with all 1's, except for the diagonal. Note: For two-level imputation models (which have `"2l"` in their names) other codes (e.g, `2` or `-2`) are also allowed.

### Value

A `blocks` object.

### See Also

`make.blocks`, `name.blocks`

### Examples

    form <- name.formulas(list(bmi + hyp ~ chl + age, chl ~ bmi))
    pred <- make.predictorMatrix(nhanes[, c("age", "chl")])
    construct.blocks(formulas = form, pred = pred)

[Package mice version 3.8.0 Index]