VPA-methods             package:FLAssess             R Documentation

_V_i_r_t_u_a_l _P_o_p_u_l_a_t_i_o_n _A_n_a_l_y_s_i_s _i_n _F_L_R

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

     Implements Pope's Virtual Population Analysis (VPA).

     The method returns an object of class 'FLVPA' class.  This extends
     the 'FLAssess' class although the 'FLVPA' class currently has the
     same slots as the 'FLAssess' class and does not add new ones.
     Objects can be created by calls of the form 'new("FLVPA", ...)' or
     by calling the 'VPA' function.

     The other arguments to 'VPA' are

_f_r_a_t_i_o A 'numeric' with default "missing"

_f_i_t._p_l_u_s_g_r_o_u_p A 'Boolean' with default TRUE

_d_e_s_c A 'character' string which appended to the desc slot of the object

     For the sake of speed, most of the calculations are carried out in
     C.

_G_e_n_e_r_i_c _f_u_n_c_t_i_o_n:

     VPA(stock, ...)

_M_e_t_h_o_d_s:


      _s_i_g_n_a_t_u_r_e(_o_b_j_e_c_t=_F_L_S_t_o_c_k) : Performs a VPA on the FLStock object.
           Other arguments are fratio, fit.plusgroup and desc, which
          are described above.

_A_u_t_h_o_r(_s):

     Laurence Kell

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

     'FLSepVPA'

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

     # use the ple4 data set
     data(ple4)
     ple4.test <- ple4
     # Remove 0s and set as 1s
     catch.n(ple4.test)[catch.n(ple4.test)==0] <- 1
     # Remove harvest and stock.n values
     stock.n(ple4.test)[] <- NA
     harvest(ple4.test)[] <- NA
     # Set Fs in final year and final ages
     harvest(ple4.test)[,"2001"] <- harvest(ple4)[,"2001"]
     harvest(ple4.test)["10",] <- harvest(ple4)["10",]
     # Run the VPA
     ple4.vpa <- VPA(ple4.test)
     # Take a look at the harvest
     plot(harvest(ple4.vpa))

