

tvctomat(rmutil)                             R Documentation

_C_r_e_a_t_e _o_r _a_d_d _t_o _a _t_i_m_e_-_v_a_r_y_i_n_g _c_o_v_a_r_i_a_t_e _(_t_v_c_o_v_) _o_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n_:

     `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 trans-
     form variables in place or by adding new variables to
     the object.

_U_s_a_g_e_:

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

_A_r_g_u_m_e_n_t_s_:

   tvcov: A list of matrices with time-varying covariate
          values for each individual (one column per vari-
          able), 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 interac-
          tions.

interaction: A pair of index numbers or names of variables
          in tvcov, with that class, for which an interac-
          tion 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.

_V_a_l_u_e_:

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

_A_u_t_h_o_r_(_s_)_:

     J.K. Lindsey

_S_e_e _A_l_s_o_:

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

_E_x_a_m_p_l_e_s_:

     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")

