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textIo.go
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textIo.go
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/*
* 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.
*/
// beam-playground:
// name: TextIO
// description: TextIO example.
// multifile: false
// context_line: 51
// categories:
// - Quickstart
// complexity: BASIC
// tags:
// - hellobeam
package main
import (
"context"
"fmt"
"github.com/apache/beam/sdks/v2/go/pkg/beam"
"github.com/apache/beam/sdks/v2/go/pkg/beam/io/textio"
"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
"github.com/apache/beam/sdks/v2/go/pkg/beam/transforms/filter"
"github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
"regexp"
"github.com/apache/beam/sdks/v2/go/pkg/beam/transforms/top"
)
var (
wordRE = regexp.MustCompile(`[a-zA-Z]+('[a-z])?`)
)
func less(a, b string) bool{
return len(a)>len(b)
}
func main() {
p, s := beam.NewPipelineWithRoot()
input := Read(s, "gs://apache-beam-samples/shakespeare/kinglear.txt")
lines := getLines(s, input)
fixedSizeLines := top.Largest(s,lines,10,less)
output(s, "Lines: ", fixedSizeLines)
words := getWords(s,lines)
fixedSizeWords := top.Largest(s,words,10,less)
output(s, "Words: ", fixedSizeWords)
err := beamx.Run(context.Background(), p)
if err != nil {
log.Exitf(context.Background(), "Failed to execute job: %v", err)
}
}
// Read reads from fiename(s) specified by a glob string and a returns a PCollection<string>.
func Read(s beam.Scope, glob string) beam.PCollection {
return textio.Read(s, glob)
}
// Read text file content line by line. resulting PCollection contains elements, where each element contains a single line of text from the input file.
func getLines(s beam.Scope, input beam.PCollection) beam.PCollection {
return filter.Include(s, input, func(element string) bool {
return element != ""
})
}
// getWords read text lines and split into PCollection of words.
func getWords(s beam.Scope, input beam.PCollection) beam.PCollection {
return beam.ParDo(s, func(line string, emit func(string)) {
for _, word := range wordRE.FindAllString(line, -1) {
emit(word)
}
}, input)
}
func output(s beam.Scope, prefix string, input beam.PCollection) {
beam.ParDo0(s, func(elements []string) {
for _, element := range elements {
fmt.Println(prefix,element)
}
}, input)
}