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# Latest
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<br>
A transform and `Combine.CombineFn` for computing the latest element in a collection.

* `Latest.globally()` takes a collection of values and produces the collection
  containing the single value with the latest implicit timestamp.
* `Latest.perKey()` takes a collection of key value pairs, and returns the
  latest value for each key, according to the implicit timestamp.

For elements with the same timestamp, the output element is arbitrarily selected.

## Examples
**Example**: compute the latest value for each session
```java
 PCollection input = ...;
 PCollection sessioned = input
    .apply(Window.into(Sessions.withGapDuration(Duration.standardMinutes(5)));
 PCollection latestValues = sessioned.apply(Latest.globally());
```

## Related transforms 
* [Reify]({{ site.baseurl }}/documentation/transforms/java/elementwise/reify)
  converts between explicit and implicit form of various Beam values
* [WithTimestamps]({{ site.baseurl }}/documentation/transforms/java/elementwise/withtimestamps)
  assigns timestamps to all the elements of a collection
