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.

_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 '"double"' (even
     if it is already '"integer"'). 'as.numeric' for factors yields the
     codes underlying the factor levels, not the numeric representation
     of the labels, see also 'factor'.

     The default method for 'is.numeric' returns 'TRUE' if its argument
     is of mode '"numeric"' (type '"double"' or type '"integer"') and
     not a factor, and 'FALSE' otherwise.  That is, 'is.integer(x) ||
     is.double(x)', or '(mode(x) == "numeric") && !is.factor(x)'.

_N_o_t_e:

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

     'numeric' and 'as.numeric' are the identical to 'double' and
     'as.double' (unless someone defines S4 methods on one of them).

_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.

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

     'double', 'integer', 'storage.mode'.

_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))

