Latest (core 2.44.0 API)

java.lang.Object
- org.apache.beam.sdk.transforms.Latest

```
public class Latest
extends java.lang.Object
```
PTransform and Combine.CombineFn for computing the latest element in a PCollection.
Example: compute the latest value for each session:
```
 PCollection<Long> input = ...;
 PCollection<Long> sessioned = input
    .apply(Window.<Long>into(Sessions.withGapDuration(Duration.standardMinutes(5)));
 PCollection<Long> latestValues = sessioned.apply(Latest.<Long>globally());
 
```
combineFn() can also be used manually, in combination with state and with the Combine transform.
For elements with the same timestamp, the element chosen for output is arbitrary.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static <T> Combine.CombineFn<TimestampedValue<T>,?,T>`	`combineFn()`	Returns a `Combine.CombineFn` that selects the latest element among its inputs.
`static <T> PTransform<PCollection<T>,PCollection<T>>`	`globally()`	Returns a `PTransform` that takes as input a `PCollection<T>` and returns a `PCollection<T>` whose contents is the latest element according to its event time, or null if there are no elements.
`static <K,V> PTransform<PCollection<KV<K,V>>,PCollection<KV<K,V>>>`	`perKey()`	Returns a `PTransform` that takes as input a `PCollection<KV<K, V>>` and returns a `PCollection<KV<K, V>>` whose contents is the latest element per-key according to its event time.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - combineFn
```
public static <T> Combine.CombineFn<TimestampedValue<T>,?,T> combineFn()
```
    Returns a Combine.CombineFn that selects the latest element among its inputs.
  - globally
```
public static <T> PTransform<PCollection<T>,PCollection<T>> globally()
```
    Returns a PTransform that takes as input a PCollection<T> and returns a PCollection<T> whose contents is the latest element according to its event time, or null if there are no elements.
    
    Type Parameters:
    
    T - The type of the elements being combined.
  - perKey
```
public static <K,V> PTransform<PCollection<KV<K,V>>,PCollection<KV<K,V>>> perKey()
```
    Returns a PTransform that takes as input a PCollection<KV<K, V>> and returns a PCollection<KV<K, V>> whose contents is the latest element per-key according to its event time.
    
    Type Parameters:
    
    K - The key type of the elements being combined.
    
    V - The value type of the elements being combined.