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Created May 31, 2016
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Apache Beam - map only keys / values of PCollection<K<?,?>>
package pl.pawelsz.apache.beam;
import org.apache.beam.sdk.transforms.SimpleFunction;
import org.apache.beam.sdk.values.KV;
public class Only {
public static class Values<TK, TI, TO> extends SimpleFunction<KV<TK, TI>, KV<TK, TO>> {
private final SimpleFunction<TI, TO> map;
public static <Tk, Ti, To> SimpleFunction<KV<Tk, Ti>, KV<Tk, To>> with(
SimpleFunction<Ti, To> map) {
return new Values<Tk, Ti, To>(map);
public Values(SimpleFunction<TI, TO> map) { = map;
public KV<TK, TO> apply(KV<TK, TI> kv) {
return KV.of(kv.getKey(), map.apply(kv.getValue()));
public static class Keys<TKI, TKO, TV> extends SimpleFunction<KV<TKI, TV>, KV<TKO, TV>> {
private final SimpleFunction<TKI, TKO> map;
public static <Tki, Tko, Tv> SimpleFunction<KV<Tki, Tv>, KV<Tko, Tv>> with(
SimpleFunction<Tki, Tko> map) {
return new Keys<Tki, Tko, Tv>(map);
public Keys(SimpleFunction<TKI, TKO> map) { = map;
public KV<TKO, TV> apply(KV<TKI, TV> kv) {
return KV.of(map.apply(kv.getKey()), kv.getValue());
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