mgu74aMAPCOUNTS          package:mgu74a.db          R Documentation

_N_u_m_b_e_r _o_f _m_a_p_p_e_d _k_e_y_s _f_o_r _t_h_e _m_a_p_s _i_n _p_a_c_k_a_g_e _m_g_u_7_4_a._d_b

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

     mgu74aMAPCOUNTS provides the "map count" (i.e. the count of mapped
     keys) for each map in package mgu74a.db.

_D_e_t_a_i_l_s:

     This "map count" information is precalculated and stored in the
     package annotation DB. This allows some quality control and is
     used by the 'checkMAPCOUNTS' function defined in AnnotationDbi to
     compare and validate different methods (like 'count.mappedkeys(x)'
     or 'sum(!is.na(as.list(x)))') for getting the "map count" of a
     given map.

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

     'mappedkeys', 'count.mappedkeys', 'checkMAPCOUNTS'

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

       mgu74aMAPCOUNTS
       mapnames <- names(mgu74aMAPCOUNTS)
       mgu74aMAPCOUNTS[mapnames[1]]
       x <- get(mapnames[1])
       sum(!is.na(as.list(x)))
       count.mappedkeys(x)   # much faster!

       ## Check the "map count" of all the maps in package mgu74a.db
       checkMAPCOUNTS("mgu74a.db")

