R: Create a Time-constant, Inter-individual Covariate (tccov)...

tcctomat {rmutil} | R Documentation

## Create a Time-constant, Inter-individual Covariate (tccov) Object

### Description

`tcctomat` creates an object of class, `tccov`, from a vector or matrix containing time-constant or inter-individual baseline covariates or a model formula. It can also combine two such objects.

Such objects can be printed. Methods are available for extracting the covariates, their names, and the formula: `covariates`, `names`, and `formula`. The method, `transform`, can transform variables in place or by adding new variables to the object.

To obtain the indexing to expand time-constant or inter-individual covariates to the size of a repeated measurements response, use `covind`.

### Usage

    tcctomat(ccov, names=NULL, units=NULL, oldccov=NULL, dataframe=TRUE,
    	description=NULL)

### Arguments

`ccov` | A vector, matrix, or dataframe containing time-constant or inter-individual baseline covariates with one row per individual, a model formula using vectors of the same size, or an object of class, `tccov`. In the first two cases, the variables may be factors; if `dataframe=FALSE`, these are transformed to indicator variables.
`units` | Optional character vector specifying units of measurements of covariates.
`names` | The names of the covariates (if the matrix does not have column names).
`oldccov` | An object of class, `tccov`, to which `ccov` is to be added.
`dataframe` | If TRUE and factor variables are present, the covariates are stored as a dataframe; if FALSE, they are expanded to indicator variables. If no factor variables are present, covariates are always stored as a matrix.
`description` | An optional named list of character vectors with names of some or all covariates containing their descriptions.

### Value

Returns an object of class, `tccov`, containing one matrix or dataframe for the covariates (`z$ccov`) with one row per individual and possibly the model formula (`z$linear`).

### Author(s)

J.K. Lindsey

### See Also

`DataMethods`, `covariates`, `description`, `formula`, `lvna`, `names`, `restovec`, `rmna`, `transform`, `tvctomat`, `units`

### Examples

    x1 <- gl(4,1)
    print(tcc1 <- tcctomat(~x1))
    covariates(tcc1)
    covariates(tcc1, name="x12")
    tcctomat(x1)
    tcctomat(x1, dataframe=FALSE)
    x2 <- c(0,0,1,1)
    print(tcc2 <- tcctomat(~x2, units="days"))
    covariates(tcc2)
    print(tcc3 <- tcctomat(~x1+x2))
    covariates(tcc3)
    covariates(tcc3, names=c("x12","x2"))
    formula(tcc3)
    names(tcc3)
    print(tcc4 <- tcctomat(data.frame(x1,x2), units=c(NA,"days")))
    covariates(tcc4)
    print(tcc5 <- tcctomat(data.frame(x1,x2), dataframe=FALSE, units=c(NA,"days")))
    covariates(tcc5)

[Package rmutil version 1.1.3 Index]