org.apache.flink.streaming.api.functions.python

Class KeyByKeySelector

java.lang.Object

org.apache.flink.streaming.api.functions.python.KeyByKeySelector

All Implemented Interfaces:

Serializable, Function, KeySelector<Row,Row>

@Internal
public class KeyByKeySelector
extends Object
implements KeySelector<Row,Row>

KeyByKeySelector is responsible for extracting the first field of the input row as key. The input row is generated by python DataStream map function in the format of (key_selector.get_key(value), value) tuple2.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
KeyByKeySelector()

Method Summary

Modifier and Type	Method and Description
Row	getKey(Row value) User-defined function that deterministically extracts the key from an object.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyByKeySelector

public KeyByKeySelector()

Method Detail

getKey

public Row getKey(Row value)

Description copied from interface: KeySelector

User-defined function that deterministically extracts the key from an object.

For example for a class:

        public class Word {
                String word;
                int count;
        }
 

The key extractor could return the word as a key to group all Word objects by the String they contain.

The code would look like this

        public String getKey(Word w) {
                return w.word;
        }
 

Specified by:

getKey in interface KeySelector<Row,Row>

Parameters:

value - The object to get the key from.

Returns:

The extracted key.