qpK2R                package:qpgraph                R Documentation

_P_a_r_t_i_a_l _c_o_r_r_e_l_a_t_i_o_n _c_o_e_f_f_i_c_i_e_n_t_s

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

     Obtains partial correlation coefficients from a given
     concentration matrix.

_U_s_a_g_e:

     qpK2R(K)

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

       K: concentration matrix.

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

     Partial correlation coefficients are obtained from a concentration
     matrix by scaling it by its diagonal and swapping the sign of the
     off-diagonal elements.

_V_a_l_u_e:

     A matrix with partial correlation coefficients.

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

     R. Castelo and A. Roverato

_R_e_f_e_r_e_n_c_e_s:

     Castelo, R. and Roverato, A. A robust procedure for Gaussian
     graphical model search from microarray data with p larger than n.
     _J. Mach. Learn. Res._, 7:2621-2650, 2006.

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

     'qpI2K'

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

     nVar <- 50 # number of variables
     maxCon <- 5  # maximum connectivity per variable

     I <- qpRndGraph(n.vtx=nVar, n.bd=maxCon)
     K <- qpI2K(I)

     R <- qpK2R(K)

     # true partial correlation coefficients of the present edges
     summary(abs(R[upper.tri(R) & I]))

     # true partial correlation coefficients of the missing edges
     summary(abs(R[upper.tri(R) & !I]))

