water.udf

Interface CMetricFunc

public interface CMetricFunc

Custom metric evaluation function. The function has 3 parts: - map: the function is executed per row and return computation state in form of array of doubles - reduce: combine 2 map results - metric: compute final metric based on the computed state

Method Summary

Modifier and Type	Method and Description
double[]	map(double[] preds, float[] yact, double weight, double offset, Model m) Compute temporary state for given row of data.
double	metric(double[] r) Get value of metric for given computation state.
double[]	reduce(double[] l, double[] r) Combine two map-call results together.

Method Detail

map

double[] map(double[] preds,
             float[] yact,
             double weight,
             double offset,
             Model m)

Compute temporary state for given row of data. The method is invoked per row represented by prediction and actual response and return "temporary computation state that is later combined together with other map-results to form final value of metric.

Parameters:

preds - predicted response value

yact - actual response value

weight - weight of row

offset - offset of row

m - model

Returns:

temporary result in form of array of doubles.

reduce

double[] reduce(double[] l,
                double[] r)

Combine two map-call results together.

Parameters:

l - a result of map call

r - a result of map call

Returns:

combined results

metric

double metric(double[] r)

Get value of metric for given computation state.

Parameters:

r - computation state

Returns:

value of metric