Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Comments¶

1. After sorting, rows in a DataFrame are sorted according to partition ID. And within each partition, rows are sorted. This property can be leverated to implement global ranking of rows. For more details, please refer to Computing global rank of a row in a DataFrame with Spark SQL. However, notice that multi-layer ranking is often more efficiency than a global ranking in big data applications.

Tips¶

1. You can use the built-in function sorted to sort any iterable collection. It always a (new) list containing sorted data. Some mutable collections (e.g., list) have thee method sort to sort elements in-place. Both sorted and Collection.sort accept an argument key for specifying customized sorting criteria.

Sort a List¶

sorted¶

If elements in a List implements the Comparable interface, you can call the method sorted to return a sorted List (in nature order).

Note: Pair in Kotin does not implement the Comparable interface!!!