Package org.apache.calcite.profile

Class SimpleProfiler

java.lang.Object

org.apache.calcite.profile.SimpleProfiler

All Implemented Interfaces:

Profiler

public class SimpleProfiler
extends Object
implements Profiler

Basic implementation of Profiler.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.calcite.profile.Profiler

Profiler.Column, Profiler.Distribution, Profiler.FunctionalDependency, Profiler.Profile, Profiler.RowCount, Profiler.Statistic, Profiler.Unique

Constructor Summary

Constructors

Constructor	Description
SimpleProfiler()

Method Summary

Modifier and Type	Method	Description
Profiler.Profile	profile(Iterable<List<Comparable>> rows, List<Profiler.Column> columns, Collection<ImmutableBitSet> initialGroups)	Creates a profile of a data set.
static double	surprise(double expected, double actual)	Returns a measure of how much an actual value differs from expected.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SimpleProfiler

public SimpleProfiler()

Method Details

profile

public Profiler.Profile profile(Iterable<List<Comparable>> rows,
 List<Profiler.Column> columns,
 Collection<ImmutableBitSet> initialGroups)

Description copied from interface: Profiler

Creates a profile of a data set.

Specified by:

profile in interface Profiler

Parameters:

rows - List of rows. Can be iterated over more than once (maybe not cheaply)

columns - Column definitions

initialGroups - List of combinations of columns that should be profiled early, because they may be interesting

Returns:

A profile describing relationships within the data set

surprise

public static double surprise(double expected,
 double actual)

Returns a measure of how much an actual value differs from expected. The formula is abs(expected - actual) / (expected + actual).

Examples:

• surprise(e, a) is always between 0 and 1;
• surprise(e, a) is 0 if e = a;
• surprise(e, 0) is 1 if e > 0;
• surprise(0, a) is 1 if a > 0;
• surprise(5, 0) is 100%;
• surprise(5, 3) is 25%;
• surprise(5, 4) is 11%;
• surprise(5, 5) is 0%;
• surprise(5, 6) is 9%;
• surprise(5, 16) is 52%;
• surprise(5, 100) is 90%;

Parameters:

expected - Expected value

actual - Actual value

Returns:

Measure of how much expected deviates from actual