xclass            package:AffyCompatible            R Documentation

(_A_d_v_a_n_c_e_d) _C_o_n_s_t_r_u_c_t _R _o_b_j_e_c_t_s _f_r_o_m _X_M_L _d_o_c_u_m_e_n_t _q_u_e_r_i_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     This function takes an xml object, created from 'readXml', and an
     xpath query referencing an element of the document,and returns an
     R object represneting the element.

     The xpath query must retrive an element, not an attribute.

_U_s_a_g_e:

     xclass(doc, xpathq, prefix = character(0))

_A_r_g_u_m_e_n_t_s:

     doc: An 'XMLInternalDocument' retrieved using 'readXml'.

  xpathq: A length-1 character string representing an xpath query into
          the document.

  prefix: A prefix used to map, when necessary, between the XML class
          name and the corresponding R class. For 'NetAffx'-based
          classes, the prefix is 'Affx'; no prefix is required for DTT
          or ARR documents.

_V_a_l_u_e:

     An R object corresponding to the class(es) referenced by the xpath
     query.

_A_u_t_h_o_r(_s):

     Martin Morgan

_R_e_f_e_r_e_n_c_e_s:

     <URL: http://www.w3.org/TR/xpath> provides a very useful
     description of xpath. Addiitonal references are in the vignette
     `Retrieving MAGE and ARR sample attributes'.

_S_e_e _A_l_s_o:

     The vignettes `Retrieving MAGE and ARR sample attributes' and
     `Annotation retrieval with NetAffxResource' for detailed
     illustration of use.

     'readXml' for appropriately reading XML documents.

_E_x_a_m_p_l_e_s:

     example(readXml)

