

NA {base}                                    R Documentation

_N_o_t _A_v_a_i_l_a_b_l_e _/ _`_`_M_i_s_s_i_n_g_'_' _V_a_l_u_e_s

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

     `NA' is a logical constant of length 1 which contains a
     missing value indicator.  `NA' can be freely coerced to
     any other vector type.

     The generic function `is.na' returns a logical vector
     of the same ``form'' as its argument `x', containing
     `TRUE' for those elements marked `NA' or `NaN' (!)  and
     `FALSE' otherwise.  `dim', `dimnames' and `names'
     attributes are preserved.

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

     NA
     is.na(x)
     is.na.data.frame(x)

_D_e_t_a_i_l_s_:

     `is.na(x)' works elementwise when `x' is a `list'.

     The method dispatching is C-internal, rather than via
     `UseMethod'.

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

     `NaN', `is.nan', etc.  and the utility function `com-
     plete.cases'.

     `na.action', `na.omit', `na.fail' on how methods can be
     tuned to deal with missing values.

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

     is.na(c(1,NA))       #> F TRUE
     is.na(paste(c(1,NA)))#> F FALSE

