Logic                  package:base                  R Documentation

_L_o_g_i_c_a_l _O_p_e_r_a_t_o_r_s

_D_e_s_c_r_i_p_t_i_o_n:

     These operators act on logical vectors.

_U_s_a_g_e:

     ! x
     x & y
     x && y
     x | y
     x || y
     xor(x, y)

_D_e_t_a_i_l_s:

     `!' indicates logical negation (NOT).

     `&' and `&&' indicate logical AND and `|' and `||' indicate
     logical OR.  The shorter form performs elementwise comparisons in
     much the same way as arithmetic operators.  The longer form
     evaluates left to right examining only the first element of each
     vector.  Evaluation proceeds only until the result is determined. 
     The longer form is appropriate for programming control-flow.

     `xor' indicates elementwise exclusive OR.

_S_e_e _A_l_s_o:

     `TRUE' or `logical'.

_E_x_a_m_p_l_e_s:

     y <- 1 + (x <- rpois(50, lambda=1.5) / 4 - 1)
     x[(x > 0) & (x < 1)]    # all x values between 0 and 1
     if (any(x == 0) || any(y == 0)) "zero encountered"

