forked from apache/beam
-
Notifications
You must be signed in to change notification settings - Fork 0
/
count.go
35 lines (30 loc) · 1.3 KB
/
count.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
// 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 stats contains transforms for statistical processing.
package stats
import (
"github.com/apache/beam/sdks/go/pkg/beam"
)
// Count counts the number of elements in a collection. It expects a
// PCollection<T> as input and returns a PCollection<KV<T,int>>. T's encoding
// must be a well-defined injection.
func Count(s beam.Scope, col beam.PCollection) beam.PCollection {
s = s.Scope("stats.Count")
pre := beam.ParDo(s, mapFn, col)
return SumPerKey(s, pre)
}
func mapFn(elm beam.T) (beam.T, int) {
return elm, 1
}