org.datavec.api.transform.stringreduce

Class StringReducer

java.lang.Object

org.datavec.api.transform.stringreduce.StringReducer

All Implemented Interfaces:

Serializable, IStringReducer

public class StringReducer
extends Object
implements IStringReducer

A StringReducer is used to take a set of examples and reduce them. The idea: suppose you have a large number of columns, and you want to combine/reduce the values in each column.
StringReducer allows you to specify different reductions for differently for different columns: min, max, sum, mean etc. See StringReducer.Builder and ReduceOp for the full list.

Uses are: (1) Reducing examples by a key (2) Reduction operations in time series (windowing ops, etc)

Author:

Alex Black

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	StringReducer.Builder

Constructor Summary

Constructors

Constructor and Description
StringReducer(List<String> inputColumns, StringReduceOp stringReduceOp, Map<String,ColumnReduction> customReductions, String outputColumnName)

Method Summary

Modifier and Type	Method and Description
List<String>	getInputColumns()
Schema	getInputSchema()
List<Writable>	reduce(List<List<Writable>> examplesList)
static Writable	reduceStringOrCategoricalColumn(StringReduceOp op, List<Writable> values)
void	setInputSchema(Schema schema)
String	toString()
Schema	transform(Schema schema) Get the output schema, given the input schema

Methods inherited from class java.lang.Object

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

Constructor Detail

StringReducer

public StringReducer(List<String> inputColumns,
                     StringReduceOp stringReduceOp,
                     Map<String,ColumnReduction> customReductions,
                     String outputColumnName)

Method Detail

setInputSchema

public void setInputSchema(Schema schema)

Specified by:

setInputSchema in interface IStringReducer

getInputSchema

public Schema getInputSchema()

Specified by:

getInputSchema in interface IStringReducer

Returns:

getInputColumns

public List<String> getInputColumns()

Specified by:

getInputColumns in interface IStringReducer

Returns:

transform

public Schema transform(Schema schema)

Get the output schema, given the input schema

Specified by:

transform in interface IStringReducer

Returns:

reduce

public List<Writable> reduce(List<List<Writable>> examplesList)

Specified by:

reduce in interface IStringReducer

Returns:

reduceStringOrCategoricalColumn

public static Writable reduceStringOrCategoricalColumn(StringReduceOp op,
                                                       List<Writable> values)

toString

public String toString()

Overrides:

toString in class Object