org.apache.spark.ml.feature

Class SQLTransformer

Object

org.apache.spark.ml.PipelineStage

org.apache.spark.ml.Transformer

org.apache.spark.ml.feature.SQLTransformer

All Implemented Interfaces:

java.io.Serializable, org.apache.spark.internal.Logging, Params, DefaultParamsWritable, Identifiable, MLWritable

public class SQLTransformer
extends Transformer
implements DefaultParamsWritable

Implements the transformations which are defined by SQL statement. Currently we only support SQL syntax like 'SELECT ... FROM __THIS__ ...' where '__THIS__' represents the underlying table of the input dataset. The select clause specifies the fields, constants, and expressions to display in the output, it can be any select clause that Spark SQL supports. Users can also use Spark SQL built-in function and UDFs to operate on these selected columns. For example, SQLTransformer supports statements like:

  SELECT a, a + b AS a_b FROM __THIS__
  SELECT a, SQRT(b) AS b_sqrt FROM __THIS__ where a > 5
  SELECT a, b, SUM(c) AS c_sum FROM __THIS__ GROUP BY a, b
 

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
SQLTransformer()
SQLTransformer(String uid)

Method Summary

Modifier and Type	Method and Description
SQLTransformer	copy(ParamMap extra) Creates a copy of this instance with the same UID and some extra params.
String	getStatement()
static SQLTransformer	load(String path)
static MLReader<T>	read()
SQLTransformer	setStatement(String value)
Param<String>	statement() SQL statement parameter.
String	toString()
Dataset<Row>	transform(Dataset<?> dataset) Transforms the input dataset.
StructType	transformSchema(StructType schema) Check transform validity and derive the output schema from the input schema.
String	uid() An immutable unique ID for the object and its derivatives.

Methods inherited from class org.apache.spark.ml.Transformer

transform, transform, transform

Methods inherited from class org.apache.spark.ml.PipelineStage

params

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.spark.ml.util.DefaultParamsWritable

write

Methods inherited from interface org.apache.spark.ml.util.MLWritable

save

Methods inherited from interface org.apache.spark.ml.param.Params

clear, copyValues, defaultCopy, explainParam, explainParams, extractParamMap, extractParamMap, get, getDefault, getOrDefault, getParam, hasDefault, hasParam, isDefined, isSet, set, set, set, setDefault, setDefault, shouldOwn

Methods inherited from interface org.apache.spark.internal.Logging

$init$, initializeForcefully, initializeLogIfNecessary, initializeLogIfNecessary, initializeLogIfNecessary$default$2, initLock, isTraceEnabled, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning, org$apache$spark$internal$Logging$$log__$eq, org$apache$spark$internal$Logging$$log_, uninitialize

Constructor Detail

SQLTransformer

public SQLTransformer(String uid)

SQLTransformer

public SQLTransformer()

Method Detail

load

public static SQLTransformer load(String path)

read

public static MLReader<T> read()

uid

public String uid()

Description copied from interface: Identifiable

An immutable unique ID for the object and its derivatives.

Specified by:

uid in interface Identifiable

Returns:

(undocumented)

statement

public final Param<String> statement()

SQL statement parameter. The statement is provided in string form.

Returns:

(undocumented)

setStatement

public SQLTransformer setStatement(String value)

getStatement

public String getStatement()

transform

public Dataset<Row> transform(Dataset<?> dataset)

Description copied from class: Transformer

Transforms the input dataset.

Specified by:

transform in class Transformer

Parameters:

dataset - (undocumented)

Returns:

(undocumented)

transformSchema

public StructType transformSchema(StructType schema)

Description copied from class: PipelineStage

Check transform validity and derive the output schema from the input schema.

We check validity for interactions between parameters during transformSchema and raise an exception if any parameter value is invalid. Parameter value checks which do not depend on other parameters are handled by Param.validate().

Typical implementation should first conduct verification on schema change and parameter validity, including complex parameter interaction checks.

Specified by:

transformSchema in class PipelineStage

Parameters:

schema - (undocumented)

Returns:

(undocumented)

copy

public SQLTransformer copy(ParamMap extra)

Description copied from interface: Params

Creates a copy of this instance with the same UID and some extra params. Subclasses should implement this method and set the return type properly. See defaultCopy().

Specified by:

copy in interface Params

Specified by:

copy in class Transformer

Parameters:

extra - (undocumented)

Returns:

(undocumented)

toString

public String toString()

Specified by:

toString in interface Identifiable

Overrides:

toString in class Object