This constructs a list (vector) of random integers in R:

Out[1]= | |

This makes a contingency table of the above data:

Out[2]= | |

Since the corresponding R object (table) has non-trivial attributes, was used to make it possible to include those.

This constructs an R data frame out of the contingency table:

Out[1]= | |

Here is the full internal form *RLink* uses to represent the above data frame:

Out[2]= | |

As you can see, is now gone, since heads used in the *RLink* internal representation of R objects (RVector and RList) can accommodate attributes.

This creates a matrix:

Out[1]= | |

Send it to R:

Out[2]= | |

Assign another attribute to R's mat variable:

Out[3]= | |

Get back a resulting R object:

Out[4]= | |

Since now it has an attribute, was used to represent it. You can also display its attributes:

Out[5]= | |

Note that the "dim" attribute is implicit in the matrix representation in the short form, so its presence does not require the use of . It is, however, explicitly present in the full form:

Out[6]= | |