is.recursive              package:base              R Documentation

_I_s _a_n _O_b_j_e_c_t _A_t_o_m_i_c _o_r _R_e_c_u_r_s_i_v_e?

_D_e_s_c_r_i_p_t_i_o_n:

     'is.atomic' returns 'TRUE' if 'x' is an atomic vector (or 'NULL')
     and 'FALSE' otherwise.

     'is.recursive' returns 'TRUE' if 'x' has a recursive (list-like)
     structure and 'FALSE' otherwise.

_U_s_a_g_e:

     is.atomic(x)
     is.recursive(x)

_A_r_g_u_m_e_n_t_s:

       x: object to be tested.

_D_e_t_a_i_l_s:

     These are generic: you can write methods to handle specific
     classes of objects, see InternalMethods.  The description here
     applies only to the default method.

     'is.atomic' is true for the atomic vector types ('"logical"',
     '"integer"', '"numeric"', '"complex"', '"character"' and '"raw"')
     and 'NULL'.

     Most types of language objects are regarded as recursive: those
     which are not are the atomic vector types, 'NULL' and symbols (as
     given by 'as.name').

_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:

     'is.list', 'is.language', etc, and the 'demo("is.things")'.

_E_x_a_m_p_l_e_s:

     is.a.r <- function(x) c(is.atomic(x), is.recursive(x))

     is.a.r(c(a=1,b=3))      # TRUE FALSE
     is.a.r(list())          # FALSE TRUE ??
     is.a.r(list(2))         # FALSE TRUE
     is.a.r(lm)              # FALSE TRUE
     is.a.r(y ~ x)           # FALSE TRUE
     is.a.r(expression(x+1)) # FALSE TRUE (not in 0.62.3!)