Add aggregate() methods for Vector
----------------------------------
Key: MAHOUT-209
URL: https://issues.apache.org/jira/browse/MAHOUT-209
Project: Mahout
Issue Type: Improvement
Components: Matrix
Environment: all
Reporter: Jake Mannix
Priority: Minor
Fix For: 0.3
As discussed in MAHOUT-165 at some point, Vector (and Matrix, but let's put
that on a separate ticket) could do with a nice exposure of methods like the
following:
{code}
// this can get optimized, of course
public double aggregate(Vector other, BinaryFunction aggregator,
BinaryFunction combiner) {
double result = 0;
for(int i=0; i<size(); i++) {
result = aggregator.apply(result, combiner.apply(getQuick(i),
other.getQuick(i)));
}
return result;
}
{code}
this is good for generalized inner products and distances. Also nice:
{code}
public double aggregate(BinaryFunction aggregator, UnaryFunction map) {
double result = 0;
for(int i=0; i<size(); i++) {
result = aggregator.apply(result, map.apply(getQuick(i)) );
}
return result;
}
{code}
Which generalizes norms and statistics (mean, median, stdDev) and things like
that (number of positive values, or negative values, etc...).
These kind of thing exists in Colt, and we could just surface it up to the top.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
