NULL package:base R Documentation
_T_h_e _N_u_l_l _O_b_j_e_c_t
_D_e_s_c_r_i_p_t_i_o_n:
‘NULL’ represents the null object in R: it is a reserved word.
NULL is often returned by expressions and functions whose value is
undefined: it is also used as the empty pairlist.
‘as.null’ ignores its argument and returns the value ‘NULL’.
‘is.null’ returns ‘TRUE’ if its argument is ‘NULL’ and ‘FALSE’
otherwise.
_U_s_a_g_e:
NULL
as.null(x, ...)
is.null(x)
_A_r_g_u_m_e_n_t_s:
x: an object to be tested or coerced.
...: ignored.
_N_o_t_e:
‘is.null’ is a primitive function.
_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.
_E_x_a_m_p_l_e_s:
is.null(list()) # FALSE (on purpose!)
is.null(integer(0))# F
is.null(logical(0))# F
as.null(list(a=1,b='c'))