Hi,
If you initially have all the data in a table T and HOUR is one the variables in table T, you can create separate tables depending upon the categorization of HOUR as follows.
T1 = T(T.HOUR>=0 & T.HOUR<=3,:);
T2 = T(T.HOUR>=4 & T.HOUR<=7,:);
T3 = T(T.HOUR>=8 & T.HOUR<=11,:);
T4 = T(T.HOUR>=12 & T.HOUR<=15,:);
T5 = T(T.HOUR>=16 & T.HOUR<=19,:);T6 = T(T.HOUR>=20 & T.HOUR<24,:);