ColumnReduction (datavec-api 1.0.0-M2.1 API)

All Superinterfaces:

ColumnOp, Operation<Schema,Schema>, Serializable
```
public interface ColumnReduction
extends Serializable, ColumnOp
```

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`ColumnMetaData`	`getColumnOutputMetaData(String newColumnName, ColumnMetaData columnInputMeta)`	Post-reduce: what is the metadata (type, etc) for this column? For example: a "count unique" operation on a String (StringMetaData) column would return an Integer (IntegerMetaData) column
`String`	`getColumnOutputName(String columnInputName)`	Post-reduce: what is the name of the column? For example, "myColumn" -> "mean(myColumn)"
`Writable`	`reduceColumn(List<Writable> columnData)`	Reduce a single column.

Methods inherited from interface org.datavec.api.transform.ColumnOp
columnName, columnNames, getInputSchema, outputColumnName, outputColumnNames, setInputSchema

Methods inherited from interface org.datavec.api.transform.Operation
transform

- Method Detail
  - reduceColumn
```
Writable reduceColumn(List<Writable> columnData)
```
    Reduce a single column. Note: The List<Writable> here is a single column in a reduction window, and NOT the single row (as is usually the case for List<Writable> instances
    
    Parameters:
    
    columnData - The Writable objects for a column
    
    Returns:
    
    Writable containing the reduced data
  - getColumnOutputName
```
String getColumnOutputName(String columnInputName)
```
    Post-reduce: what is the name of the column? For example, "myColumn" -> "mean(myColumn)"
    
    Parameters:
    
    columnInputName - Name of the column before reduction
    
    Returns:
    
    Name of the column after the reduction
  - getColumnOutputMetaData
```
ColumnMetaData getColumnOutputMetaData(String newColumnName,
                                       ColumnMetaData columnInputMeta)
```
    Post-reduce: what is the metadata (type, etc) for this column? For example: a "count unique" operation on a String (StringMetaData) column would return an Integer (IntegerMetaData) column
    
    Parameters:
    
    columnInputMeta - Metadata for the column, before reduce
    
    Returns:
    
    Metadata for the column, after the reduction