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))

