numeric                 package:base                 R Documentation

_N_u_m_e_r_i_c _V_e_c_t_o_r_s

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

     Creates or tests for objects of type '"numeric"'.

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

     numeric(length = 0)
     as.numeric(x, ...)
     is.numeric(x)

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

  length: desired length.

       x: object to be coerced or tested.

     ...: further arguments passed to or from other methods.

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

     'as.numeric' is a generic function, but methods must be written
     for 'as.double', which it calls.

     'is.numeric' is generic: you can write methods to handle specific
     classes of objects, see InternalMethods.

     Note that factors are false for 'is.numeric' since there is a
     '"factor"' method.

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

     'numeric' creates a real vector of the specified length.  The
     elements of the vector are all equal to '0'.

     'as.numeric' attempts to coerce its argument to numeric type
     (either integer or real). 'as.numeric' for factors yields the
     codes underlying the factor levels, not the numeric representation
     of the labels.

     'is.numeric' returns 'TRUE' if its argument is of type numeric or
     type integer and 'FALSE' otherwise.

_N_o_t_e:

     _R has no single precision data type.  All real numbers are stored
     in double precision format_.

_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:

     as.numeric(c("-.1"," 2.7 ","B")) # (-0.1, 2.7, NA)  +  warning
     as.numeric(factor(5:10))

