Commit after completing subclass.ds.
Typo corrected.
Function names change to *.DS instead of *.ds because of complaint of non compatibility with S when names are similar to those in R like mean.ds.
Function product.ds renamed productDS.
Obsolete function removed from aggregate and assign functions.
Function 'subclassDS' completed.
Bug sorted.
Bug sorted.
Bug sorted.
Bug sorted.
Bug sorted and comment in example re-worded.
Bug sorted.
Files containing internal functions now hidden.
Last commit reversed.
Added: if class has no observations, generate empty subset (i.e. subset with NAs).
Messages amended and bug sorted.
Lines refering to empty subsets removed.
Function 'subsetDS' added.
function 'subsetDS' completed.
Function 'subsetDS' added to list of assign functions in 'Description' file.