dim                   package:base                   R Documentation

_D_i_m_e_n_s_i_o_n_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 dimension of an object.

_U_s_a_g_e:

     dim(x)
     dim(x) <- value

_A_r_g_u_m_e_n_t_s:

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

   value: For the default method, either 'NULL' or a numeric vector,
          which is coerced to integer (by truncation).

_D_e_t_a_i_l_s:

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

     'dim' has a method for 'data.frame's, which returns the lengths of
     the 'row.names' attribute of 'x' and of 'x' (as the numbers of
     rows and columns respectitvely).

     These functions are primitive, so argument names are ignored (but
     this might not be true of their methods).

_V_a_l_u_e:

     For an array (and hence in particular, for a matrix) 'dim'
     retrieves the 'dim' attribute of the object.  It is 'NULL' or a
     vector of mode 'integer'.

     The replacement method changes the '"dim"' attribute (provided the
     new value is compatible) and removes any '"dimnames"' _and_
     '"names"' attributes.

_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:

     'ncol', 'nrow' and 'dimnames'.

_E_x_a_m_p_l_e_s:

     x <- 1:12 ; dim(x) <- c(3,4)
     x

     # simple versions of nrow and ncol could be defined as follows
     nrow0 <- function(x) dim(x)[1]
     ncol0 <- function(x) dim(x)[2]