
org.apache.flink.ml.feature.tokenizer.Tokenizer Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.flink.ml.feature.tokenizer;
import org.apache.flink.ml.api.Transformer;
import org.apache.flink.ml.param.Param;
import org.apache.flink.ml.util.ParamUtils;
import org.apache.flink.ml.util.ReadWriteUtils;
import org.apache.flink.table.api.Expressions;
import org.apache.flink.table.api.Table;
import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
import org.apache.flink.table.expressions.Expression;
import org.apache.flink.table.functions.ScalarFunction;
import org.apache.flink.util.Preconditions;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import static org.apache.flink.table.api.Expressions.$;
/**
* A Transformer which converts the input string to lowercase and then splits it by white spaces.
*/
public class Tokenizer implements Transformer, TokenizerParams {
private final Map, Object> paramMap = new HashMap<>();
public Tokenizer() {
ParamUtils.initializeMapWithDefaultValues(paramMap, this);
}
@Override
public Table[] transform(Table... inputs) {
Preconditions.checkArgument(inputs.length == 1);
Expression tokenizerUdf =
Expressions.call(TokenizerUdf.class, $(getInputCol())).as(getOutputCol());
Table output = inputs[0].addColumns(tokenizerUdf);
return new Table[] {output};
}
@Override
public void save(String path) throws IOException {
ReadWriteUtils.saveMetadata(this, path);
}
@Override
public Map, Object> getParamMap() {
return paramMap;
}
public static Tokenizer load(StreamTableEnvironment tEnv, String path) throws IOException {
return ReadWriteUtils.loadStageParam(path);
}
/**
* The main logic of {@link Tokenizer}, which converts the input string to an array of tokens.
*/
public static class TokenizerUdf extends ScalarFunction {
public String[] eval(String input) {
return input.toLowerCase().split("\\s");
}
}
}
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