Dear all, I have a date frame like this: X Y Z 22 24 4.3 2.3 3.4 5.3 ..... .... 57.2 23.4 34 What my purpose is: to sort the data frame by either X, Y or Z. sample output is (sorted by X) : X Y Z 2.3 3.4 5.3 ..... ...... 22 24 4.3 ... 57.2 23.4 34 I have no idea how to use sort, order or rank functions. Please help me out. Thanks! Leaf