Return the size of this Frame in memory.

The function attempts to compute the total memory size of the frame as precisely as possible. In particular, it takes into account not only the size of data in columns, but also sizes of all auxiliary internal structures.

Special cases: if frame is a view (say, d2 = DT[:1000, :]), then the reported size will not contain the size of the data, because that data “belongs” to the original datatable and is not copied. However if a frame selects only a subset of columns (say, d3 = DT[:, :5]), then a view is not created and instead the columns are copied by reference. Frame d3 will report the “full” size of its columns, even though they do not occupy any extra memory compared to DT. This behavior may be changed in the future.

This function is not intended for manual use. Instead, in order to get the size of a frame DT, call sys.getsizeof(DT).