XDataFrame-utils           package:IRanges           R Documentation

_X_D_a_t_a_F_r_a_m_e _u_t_i_l_i_t_y _f_u_n_c_t_i_o_n_s

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

     Utility functions for manipulating 'XDataFrame' objects.

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

     ## S4 method for signature 'expressionORlanguage,
     ##   XDataFrame':
     eval(expr, envir, enclos = parent.frame())

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

    expr: The 'expression', 'call', or 'name' to be evaluated.

   envir: The 'XDataFrame' object in which to evaluate 'expr'.

  enclos: The 'environment' in which to look for symbols that do not
          exist in the environment formed from 'XDataFrame'.

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

     The 'eval' method converts the 'XDataFrame' object specified in
     'envir' to an 'environmnent', with 'enclos' as its parent, and
     then evaluates 'expr' within that environment. As when evaluating
     within an ordinary 'data.frame', the environment formed from an
     'XDataFrame' contains a symbol for each column name which refers
     to the object stored in that column.

     The objects are not actually copied into the environment. Rather,
     they are dynamically bound using 'makeActiveBinding'. This
     prevents unnecessary copying of the data from the external vectors
     into R vectors. The values are cached, so that the data is not
     copied every time the symbol is accessed.

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

     The result of expression evaluation.

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

     Michael Lawrence

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

     'FilterRules' objects, which can be evaluated on a 'XDataFrame',
     and the base 'eval' function.

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

       score <- c(10L, 2L, NA)
       rd <- XDataFrame(score)
       eval(quote(score > 3), rd)

