tvalentyn commented on code in PR #32445:
URL: https://github.com/apache/beam/pull/32445#discussion_r1803471797
##########
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Flatten.java:
##########
@@ -82,6 +83,81 @@ public static <T> Iterables<T> iterables() {
return new Iterables<>();
}
+ /**
+ * Returns a {@link PTransform} that flattens the input {@link PCollection}
with a given a {@link
Review Comment:
```suggestion
* Returns a {@link PTransform} that flattens the input {@link
PCollection} with a given {@link
```
##########
sdks/python/apache_beam/examples/snippets/snippets.py:
##########
@@ -1143,6 +1143,39 @@ def model_multiple_pcollections_flatten(contents,
output_path):
merged | beam.io.WriteToText(output_path)
+def model_multiple_pcollections_flatten_with(contents, output_path):
+ """Merging a PCollection with FlattenWith."""
+ some_hash_fn = lambda s: ord(s[0])
+ partition_fn = lambda element, partitions: some_hash_fn(element) % partitions
+ import apache_beam as beam
+ with TestPipeline() as pipeline: # Use TestPipeline for testing.
+
+ # Partition into deciles
+ partitioned = pipeline | beam.Create(contents) | beam.Partition(
+ partition_fn, 3)
+ pcoll1 = partitioned[0]
+ pcoll2 = partitioned[1]
+ pcoll3 = partitioned[2]
+ SomeTransform = lambda: beam.Map(lambda x: x)
Review Comment:
Should we have other example for merging with a transform output? feel free
to create a bug to add it. examples are just important as having the
capability, so i think we should highlight these everywhere (beam playground,
snippets, website docs, etc). Can be with follow up /starter bugs if you don't
have time to do all that in one change.
##########
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Flatten.java:
##########
@@ -82,6 +83,81 @@ public static <T> Iterables<T> iterables() {
return new Iterables<>();
}
+ /**
+ * Returns a {@link PTransform} that flattens the input {@link PCollection}
with a given a {@link
+ * PCollection} resulting in a {@link PCollection} containing all the
elements of both {@link
+ * PCollection}s as its output.
+ *
+ * <p>This is equivalent to creating a {@link PCollectionList} containing
both the input and
+ * {@code other} and then applying {@link #pCollections()}, but has the
advantage that it can be
+ * more easily used inline.
+ *
+ * <p>Both {@cpde PCollections} must have equal {@link WindowFn}s. The
output elements of {@code
+ * Flatten<T>} are in the same windows and have the same timestamps as their
corresponding input
+ * elements. The output {@code PCollection} will have the same {@link
WindowFn} as both inputs.
+ *
+ * @param other the other PCollection to flatten with the input
+ * @param <T> the type of the elements in the input and output {@code
PCollection}s.
+ */
+ public static <T> PTransform<PCollection<T>, PCollection<T>>
with(PCollection<T> other) {
+ return new FlattenWithPCollection<>(other);
+ }
+
+ /** Implementation of {@link #with(PCollection)}. */
+ private static class FlattenWithPCollection<T>
+ extends PTransform<PCollection<T>, PCollection<T>> {
+ // We only need to access this at pipeline construction time.
+ private final transient PCollection<T> other;
+
+ public FlattenWithPCollection(PCollection<T> other) {
+ this.other = other;
+ }
+
+ @Override
+ public PCollection<T> expand(PCollection<T> input) {
+ return PCollectionList.of(input).and(other).apply(pCollections());
+ }
+
+ @Override
+ public String getKindString() {
+ return "Flatten.With";
+ }
+ }
+
+ /**
+ * Returns a {@link PTransform} that flattens the input {@link PCollection}
with the output of
+ * another {@link PTransform} resulting in a {@link PCollection} containing
all the elements of
+ * both the input {@link PCollection}s and the output of the given {@link
PTransform} as its
+ * output.
+ *
+ * <p>This is equivalent to creating a {@link PCollectionList} containing
both the input and the
+ * output of {@code other} and then applying {@link #pCollections()}, but
has the advantage that
+ * it can be more easily used inline.
+ *
+ * <p>Both {@cpde PCollections} must have equal {@link WindowFn}s. The
output elements of {@code
Review Comment:
```suggestion
* <p>Both {@code PCollections} must have equal {@link WindowFn}s. The
output elements of {@code
```
##########
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Tee.java:
##########
@@ -0,0 +1,91 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.beam.sdk.transforms;
+
+import java.util.function.Consumer;
+import org.apache.beam.sdk.values.PCollection;
+import org.apache.beam.sdk.values.PCollectionTuple;
+
+/**
+ * A PTransform that returns its input, but also applies its input to an
auxiliary PTransform, akin
+ * to the shell {@code tee} command.
Review Comment:
```suggestion
* to the shell {@code tee} command, which is named after the T-splitter
used in plumbing.
```
##########
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Flatten.java:
##########
@@ -82,6 +83,81 @@ public static <T> Iterables<T> iterables() {
return new Iterables<>();
}
+ /**
+ * Returns a {@link PTransform} that flattens the input {@link PCollection}
with a given a {@link
+ * PCollection} resulting in a {@link PCollection} containing all the
elements of both {@link
+ * PCollection}s as its output.
+ *
+ * <p>This is equivalent to creating a {@link PCollectionList} containing
both the input and
+ * {@code other} and then applying {@link #pCollections()}, but has the
advantage that it can be
+ * more easily used inline.
+ *
+ * <p>Both {@cpde PCollections} must have equal {@link WindowFn}s. The
output elements of {@code
+ * Flatten<T>} are in the same windows and have the same timestamps as their
corresponding input
+ * elements. The output {@code PCollection} will have the same {@link
WindowFn} as both inputs.
+ *
+ * @param other the other PCollection to flatten with the input
+ * @param <T> the type of the elements in the input and output {@code
PCollection}s.
+ */
+ public static <T> PTransform<PCollection<T>, PCollection<T>>
with(PCollection<T> other) {
+ return new FlattenWithPCollection<>(other);
+ }
+
+ /** Implementation of {@link #with(PCollection)}. */
+ private static class FlattenWithPCollection<T>
+ extends PTransform<PCollection<T>, PCollection<T>> {
+ // We only need to access this at pipeline construction time.
+ private final transient PCollection<T> other;
+
+ public FlattenWithPCollection(PCollection<T> other) {
+ this.other = other;
+ }
+
+ @Override
+ public PCollection<T> expand(PCollection<T> input) {
+ return PCollectionList.of(input).and(other).apply(pCollections());
+ }
+
+ @Override
+ public String getKindString() {
+ return "Flatten.With";
Review Comment:
Merge.With might be a possible alternative name. but maybe it adds more
confusion since we have a pre-existing `Flatten` already for a similar concept.
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