dimnames                package:base                R Documentation

_D_i_m_n_a_m_e_s _o_f _a_n _O_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n:

     Retrieve or set the dimnames of an object.

_U_s_a_g_e:

     dimnames(x)
     dimnames(x) <- value

_A_r_g_u_m_e_n_t_s:

       x: an R object, for example a matrix, array or data frame.

   value: a possible value for 'dimnames(x)': see the Value section.

_D_e_t_a_i_l_s:

     The functions 'dimnames' and 'dimnames<-' are generic.

     For an 'array' (and hence in particular, for a 'matrix'), they
     retrieve or set the 'dimnames' attribute (see attributes) of the
     object.  A list 'value' can have names, and these will be used to
     label the dimensions of the array where appropriate.

     The replacement method for arrays/matrices coerces vector and
     factor elements of 'value' to character, but does not dispatch
     methods for 'as.character'.  It coerces zero-length elements to
     'NULL'.

     Both have methods for data frames.  The dimnames of a data frame
     are its 'row.names' and its 'names'.  For the replacement method
     each component of 'value' will be coerced by 'as.character'.

     For a 1D matrix the 'names' are the same thing as the (only)
     component of the 'dimnames'.

_V_a_l_u_e:

     The dimnames of a matrix or array can be 'NULL' or a list of the
     same length as 'dim(x)'.  If a list, its components are either
     'NULL' or a character vector with positive length of the
     appropriate dimension of 'x'.

     For the '"data.frame"' method both dimnames are character vectors,
     and the rownames must contain no duplicates nor missing values.

_N_o_t_e:

     Setting components of the dimnames, e.g. 'dimnames(A)[[1]] <-
     value' is a common paradigm, but note that it will not work if the
     value assigned is 'NULL'.  Use 'rownames' instead, or (as it does)
     manipulate the whole dimnames list.

_R_e_f_e_r_e_n_c_e_s:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

_S_e_e _A_l_s_o:

     'rownames', 'colnames'; 'array', 'matrix', 'data.frame'.

_E_x_a_m_p_l_e_s:

     ## simple versions of rownames and colnames
     ## could be defined as follows
     rownames0 <- function(x) dimnames(x)[[1]]
     colnames0 <- function(x) dimnames(x)[[2]]

