AsIs                  package:base                  R Documentation

_I_n_h_i_b_i_t _I_n_t_e_r_p_r_e_t_a_t_i_o_n/_C_o_n_v_e_r_s_i_o_n _o_f _O_b_j_e_c_t_s

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

     Change the class of an object to indicate that it should be
     treated ``as is''.

_U_s_a_g_e:

     I(x)

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

       x: an object

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

     Function `I' has two main uses.

        *  In function `data.frame'.  Protecting an object by enclosing
           it in `I()' in a call to data.frame inhibits the conversion
           of character vectors to factors.  `I' can also be used to
           protect objects which are to be added to a data frame, or
           converted to a data frame via `as.data.frame'.

           It achieves this by prepending the class `"AsIs"' to the
           object's classes.  Class `"AsIs"' has a few of its own
           methods, including for `[', `as.data.frame', `print' and
           `format'.

        *  In function `formula'.  There it is used to inhibit the
           interpretation of  operators such as `"+"', `"-"', `"*"' and
           `"^"' as formula operators, so they are used as arithmetical
           operators.  This is interpreted as a symbol by
           `terms.formula'.

_V_a_l_u_e:

     A copy of the object with class `"AsIs"' prepended to the
     class(es).

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

     `data.frame', `formula'

