tvctomat {rmutil}R Documentation

Create or add to a time-varying covariate (tvcov) object

Description

tvctovmat creates an object of class, tvcov, from a list of matrices with time-varying covariates for each individual or one matrix or dataframe of such covariate values or combines two such objects. It can also add interactions among covariates.

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

Usage

tvctomat(tvcov, names=NULL, interaction=NULL, ccov=NULL,
        oldtvcov=NULL, dataframe=TRUE)

Arguments

tvcov A list of matrices with time-varying covariate values for each individual (one column per variable), one matrix or dataframe of such covariate values (when there is only one such covariate), or an object of class, tvcov. In the first two cases, the variables may be factors.
names The names of the time-varying covariates in tvcov (if the matrices do not have column names) or the names of the time-constant covariates for interactions.
interaction A pair of index numbers or names of variables in tvcov, with that class, for which an interaction is to be added or, if ccov is provided, a set of such names of time-varying covariates for creating interactions with the time-constant covariates.
ccov Time-constant covariates for which an interaction is to be introduced with time-varying covariates in tvcov.
oldtvcov An object of class, tvcov, to which tvcov 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.

Value

Returns an object of class, tvcov, containing a matrix for the covariates (z$tvcov) with one row per response per individual and a vector giving the number of observations per individual (z$nobs).

Author(s)

J.K. Lindsey

See Also

gettvc, read.list, restovec, rmna, tcctomat, transform.

Examples

z <- matrix(rpois(20,5),ncol=5)
print(tvc <- tvctomat(z))
covariates(tvc)
names(tvc)
v <- data.frame(matrix(rep(c("a","b","c","d","e"),4),ncol=5))
print(tvc2 <- tvctomat(v, oldtvc=tvc))
covariates(tvc2)
print(tvc3 <- tvctomat(v, oldtvc=tvc, dataframe=T))
covariates(tvc3)
print(tvc4 <- tvctomat(tvc3, interaction=c("z","v")))
covariates(tvc4)
x1 <- 1:4
x2 <- gl(4,1)
xx <- tcctomat(data.frame(x1,x2))
tvctomat(tvc3, interaction="z", ccov=xx)
tvctomat(tvc3, interaction="z", ccov=xx, names="x1")
tvctomat(tvc3, interaction="z", ccov=xx, names=c("x22","x23","x24"))
xx <- tcctomat(data.frame(x1,x2), dataframe=T)
tvctomat(tvc3, interaction="z", ccov=xx)
tvctomat(tvc3, interaction="z", ccov=xx, names="x1")
tvctomat(tvc3, interaction="z", ccov=xx, names="x2")

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