EmptyMatrix is a DataMatrix variant that does not use a file. Like the name says, it’s an empty instance, which only has column names and row names. A typical instantiation of an EmptyMatrix instance is like this:
>>> matrix = EmptyMatrix(row_names=["1","2","3"],column_names=["Name","Surname"])
in this case, we create an EmptyMatrix instance consisting of three rows and two columns. Columns contain only empty lists when the instance is created: we can add column data by using assignments (e.g. matrix["Name"] = XXX) or by inserting or appending rows using the append* and insert* methods (which are inherited from DataMatrix).
Aside those details, EmptyMatrix instances behave exactly like their DataMatrix equivalents.