/**
* CSV output contains one recommendation per line, and each line is of the form {@code
* itemID,strength}, like {@code "ABC",0.53}. Strength is an opaque indicator of the relative
* quality of the recommendation.
*/
final void output(ServletResponse response, Iterable<IDValue> items) throws IOException {
Writer writer = response.getWriter();
for (IDValue item : items) {
writer.write(DelimitedDataUtils.encode(item.getID(), Float.toString(item.getValue())));
writer.write('\n');
}
}
private static String setToString(LongFloatMap map) {
LongPrimitiveIterator it = map.keySetIterator();
Collection<String> keyStrings = Lists.newArrayListWithCapacity(map.size());
while (it.hasNext()) {
keyStrings.add(Long.toString(it.nextLong()));
}
return DelimitedDataUtils.encode(',', keyStrings);
}
@Override
public void process(Pair<Long, Iterable<NumericIDValue>> input, Emitter<String> emitter) {
StringLongMapping mapping = idMapping.getIDMapping();
Iterable<NumericIDValue> recs = TopN.selectTopN(input.second().iterator(), numRecs);
String userID = mapping.toString(input.first());
for (NumericIDValue rec : recs) {
emitter.emit(
DelimitedDataUtils.encode(
',', userID, mapping.toString(rec.getID()), Float.toString(rec.getValue())));
}
}