MapElements

Javadoc

Applies a simple 1-to-1 mapping function over each element in the collection.

Examples

Example 1: providing the mapping function using a SimpleFunction

Example 2: providing the mapping function using a SerializableFunction, which allows the use of Java 8 lambdas. Due to type erasure, you need to provide a hint indicating the desired return type.

PCollection<String>lines=Create.of("Hello World","Beam is fun");PCollection<Integer>lineLengths=lines.apply(MapElements.into(TypeDescriptors.integers()).via((Stringline)->line.length()));

Related transforms

• FlatMapElements behaves the same as Map, but for each input it may produce zero or more outputs.
• Filter is useful if the function is just deciding whether to output an element or not.
• ParDo is the most general element-wise mapping operation, and includes other abilities such as multiple output collections and side-inputs.