

_A_p_p_l_y _a _F_u_n_c_t_i_o_n _O_v_e_r _a _L_i_s_t

     lapply(X, fun, ...)
     sapply(X, fun, ..., simplify = TRUE)

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

       X: list (or vector for `sapply') to be used.

     fun: the function to be applied.  In the case of func-
          tions like `+', `%*%', etc., the function name
          must be quoted.

     ...: optional arguments to `fun'.

simplify: logical; should the result be simplified to a vec-
          tor if possible?

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

     `lapply' returns a list of the same length as `X'.
     Each element of which is the result of applying `fun'
     to the corresponding element of `X'.

     `sapply' is a ``user-friendly'' version of `lapply'
     also accepting vectors as `X', and returning a vector
     or array with `dimnames' if appropriate.

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

     `apply', `tapply'.

_E_x_a_m_p_l_e_s:

     x <- list(a = 1:10, beta = exp(-3:3), logic = c(T,F,F,T))
     # compute the list mean for each list element
     lapply(x,mean)
     # median and quartiles for each list element
     lapply(x, quantile, probs = 1:3/4)
     sapply(x, quantile)
     sapply(sapply(3:9, seq), fivenum)

