mean                  package:base                  R Documentation

_A_r_i_t_h_m_e_t_i_c _M_e_a_n

_D_e_s_c_r_i_p_t_i_o_n:

     Generic function for the (trimmed) arithmetic mean.

_U_s_a_g_e:

     mean(x, ...)

     ## Default S3 method:
     mean(x, trim = 0, na.rm = FALSE, ...)

_A_r_g_u_m_e_n_t_s:

       x: An R object.  Currently there are methods for numeric/logical
          vectors and date, date-time and time interval objects, and
          for data frames all of whose columns have a method.  Complex
          vectors are allowed for 'trim = 0', only.

    trim: the fraction (0 to 0.5) of observations to be trimmed from
          each end of 'x' before the mean is computed. Values of trim
          outside that range are taken as the nearest endpoint. 

   na.rm: a logical value indicating whether 'NA' values should be
          stripped before the computation proceeds.

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

_V_a_l_u_e:

     For a data frame, a named vector with the appropriate method being
     applied column by column.

     If 'trim' is zero (the default), the arithmetic mean of the values
     in 'x' is computed, as a numeric or complex vector of length one. 
     If 'x' is not logical (coerced to numeric), numeric (including
     integer) or complex, 'NA' is returned, with a warning.

     If 'trim' is non-zero, a symmetrically trimmed mean is computed
     with a fraction of 'trim' observations deleted from each end
     before the mean is computed.

_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:

     'weighted.mean', 'mean.POSIXct', 'colMeans' for row and column
     means.

_E_x_a_m_p_l_e_s:

     x <- c(0:10, 50)
     xm <- mean(x)
     c(xm, mean(x, trim = 0.10))

     mean(USArrests, trim = 0.2)