| // 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 main |
| |
| import ( |
| "context" |
| "flag" |
| |
| "github.com/apache/beam/sdks/go/pkg/beam" |
| "github.com/apache/beam/sdks/go/pkg/beam/log" |
| "github.com/apache/beam/sdks/go/pkg/beam/transforms/stats" |
| "github.com/apache/beam/sdks/go/pkg/beam/transforms/top" |
| "github.com/apache/beam/sdks/go/pkg/beam/x/beamx" |
| "github.com/apache/beam/sdks/go/pkg/beam/x/debug" |
| ) |
| |
| type Grade struct { |
| Name string |
| GPA float32 |
| } |
| |
| func less(a, b Grade) bool { |
| return a.GPA < b.GPA |
| } |
| |
| func alphabetically(a, b Grade) bool { |
| return a.Name < b.Name |
| } |
| |
| func printTopFn(ctx context.Context, list []Grade) { |
| log.Infof(ctx, "TOP %v student(s):", len(list)) |
| for i, student := range list { |
| log.Infof(ctx, " %v:\t%v\t(GPA: %v)", i+1, student.Name, student.GPA) |
| } |
| } |
| |
| func main() { |
| flag.Parse() |
| beam.Init() |
| |
| ctx := context.Background() |
| |
| data := []Grade{ |
| {"Adam", 2.3}, |
| {"Alice", 3.8}, |
| {"Alex", 2.5}, |
| {"Bart", 3.2}, |
| {"Bob", 3.9}, |
| {"Brittney", 3.1}, |
| {"Brenda", 3.5}, |
| {"Chad", 1.1}, |
| } |
| |
| log.Info(ctx, "Running grades") |
| |
| p := beam.NewPipeline() |
| s := p.Root() |
| students := beam.CreateList(s, data) |
| |
| // (1) Print top 3 students overall by GPA |
| |
| best := top.Largest(s, students, 3, less) |
| beam.ParDo0(s, printTopFn, best) |
| |
| // (2) Print top student per initial (then ordered by name) |
| |
| keyed := beam.ParDo(s, func(g Grade) (string, Grade) { |
| return g.Name[:1], g |
| }, students) |
| keyedBest := top.LargestPerKey(s, keyed, 1, less) |
| unkeyed := beam.Explode(s, beam.DropKey(s, keyedBest)) |
| |
| altBest := top.Smallest(s, unkeyed, 30, alphabetically) |
| beam.ParDo0(s, printTopFn, altBest) |
| |
| // (3) Print Chad |
| |
| chad := top.Smallest(s, students, 1, less) |
| beam.ParDo0(s, printTopFn, chad) |
| |
| // (4) Print min/max/sum/mean grades |
| |
| grades := beam.ParDo(s, func(g Grade) float32 { return g.GPA }, students) |
| debug.Printf(s, "Min: %v", stats.Min(s, grades)) |
| debug.Printf(s, "Max: %v", stats.Max(s, grades)) |
| debug.Printf(s, "Sum: %v", stats.Sum(s, grades)) |
| debug.Printf(s, "Mean: %v", stats.Mean(s, grades)) |
| |
| if err := beamx.Run(ctx, p); err != nil { |
| log.Exitf(ctx, "Failed to execute job: %v", err) |
| } |
| } |