

duplicated {base}                            R Documentation

_D_e_t_e_r_m_i_n_e _D_u_p_l_i_c_a_t_e _E_l_e_m_e_n_t_s

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

     Determines which elements of a vector are duplicates of
     elements with smaller subscripts, and returns a logical
     vector indicating which elements are duplicates.

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

     duplicated(x)

_A_r_g_u_m_e_n_t_s_:

       x: an atomic vector

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

     `unique'.

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

     x <- c(9:20, 1:5, 3:7, 0:8)
     ## extract unique elements
     (xu <- x[!duplicated(x)])
     all(xu == unique(x)) # TRUE, but unique(x) is more efficient
     all(0:20  == sort(x[!duplicated(x)]))

