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import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import mapreduce.MapReduce;
public class InvertedIndex {
public Map<String, List<String>> run(List<String> filenames) {
List<Document> inputs = new LinkedList<>();
for (String filename : filenames) {
inputs.add(new Document(filename, FileParser.parse(filename)));
}
// TODO: instantiate a MapReduce object with correct input, key, value, and output types
MapReduce<Document, String, String, List<String>> mapReduce = new MapReduce<>();
// TODO: set the mapper and reducer suppliers, and set the inputs
mapReduce.setMapperSupplier(Mapper::new);
mapReduce.setReducerSupplier(Reducer::new);
mapReduce.setInput(inputs);
// TODO: execute the MapReduce object and return the result
return mapReduce.call();
}
class Document {
String name;
List<String> words;
public Document(String name, List<String> words) {
this.name = name;
this.words = words;
}
}
class Mapper
extends mapreduce.Mapper<Document, String, String> {
@Override
public Map<String, String> compute() {
// TODO: implement the Map function for inverted index
Map<String, String> map = new HashMap<>();
for (String word : input.words) {
map.put(word, input.name);
}
return map;
}
}
class Reducer
extends mapreduce.Reducer<String, String, List<String>> {
@Override
public List<String> compute() {
// TODO: implement the Reduce function for inverted index
List<String> list = new LinkedList<>();
list.addAll(valueList);
return list;
}
}
}
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