[MATH-1046] math3.stat.Frequency: Allow Null keys (comparable objects)

• Type: Improvement
• Status: Closed
• Priority: Trivial
• Resolution: Not A Problem
• Affects Version/s: 3.2
• Fix Version/s: 3.2
• Labels: features

Environment

Linux, JDK 7

• Assignee: Unassigned
• Reporter: Hugo Ferrira
• Created: 24/Oct/13 10:59
• Updated: 24/Oct/13 19:15
• Resolved: 24/Oct/13 14:53

Description

The class math3.stat.Frequency uses a TreeMap which does not allow
for the use of null keys (public void addValue(Comparable<?> v) with v = null). I am analyzing data (matrix) whose values may
contain nulls. I need to get the counts for elements in a given column.
This includes knowing how many are null. This information will be used
for data cleaning/pre-processing.

A simple change would be substituting TreeMap with java.util.HashMap<K,V>.