Solodye commented on a change in pull request #193: [WIP][HIVEMALL-253-2]
map_roulette UDF
URL: https://github.com/apache/incubator-hivemall/pull/193#discussion_r291990428
##########
File path: core/src/main/java/hivemall/tools/map/MapRouletteUDF.java
##########
@@ -49,164 +39,171 @@
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.MapObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
+import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import
org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
+import com.clearspring.analytics.util.Preconditions;
+
/**
* The map_roulette returns a map key based on weighted random sampling of map
values.
*/
-@Description(name = "map_roulette", value = "_FUNC_(Map<K, number> map)"
- + " - Returns a map key based on weighted random sampling of map
values")
+@Description(name = "map_roulette",
+ value = "_FUNC_(Map<K, number> map [, (const) int/bigint seed])"
+ + " - Returns a map key based on weighted random sampling of
map values."
+ + " Average of values is used for null values")
@UDFType(deterministic = false, stateful = false) // it is false because it
return value base on probability
public final class MapRouletteUDF extends GenericUDF {
private transient MapObjectInspector mapOI;
private transient PrimitiveObjectInspector valueOI;
+ @Nullable
+ private transient PrimitiveObjectInspector seedOI;
+
+ @Nullable
+ private transient Random _rand;
@Override
- public ObjectInspector initialize(ObjectInspector[] arguments) throws
UDFArgumentException {
- if (arguments.length != 1) {
+ public ObjectInspector initialize(ObjectInspector[] argOIs) throws
UDFArgumentException {
+ if (argOIs.length != 1 && argOIs.length != 2) {
throw new UDFArgumentLengthException(
- "Expected exactly one argument for map_roulette: " +
arguments.length);
+ "Expected exactly one argument for map_roulette: " +
argOIs.length);
}
- if (arguments[0].getCategory() != ObjectInspector.Category.MAP) {
+ if (argOIs[0].getCategory() != ObjectInspector.Category.MAP) {
throw new UDFArgumentTypeException(0,
- "Only map type argument is accepted but got " +
arguments[0].getTypeName());
+ "Only map type argument is accepted but got " +
argOIs[0].getTypeName());
}
- mapOI = HiveUtils.asMapOI(arguments[0]);
- ObjectInspector keyOI = mapOI.getMapKeyObjectInspector();
-
- //judge valueOI is a number
- valueOI = (PrimitiveObjectInspector)
mapOI.getMapValueObjectInspector();
- switch (valueOI.getTypeName()) {
- case INT_TYPE_NAME:
- case DOUBLE_TYPE_NAME:
- case BIGINT_TYPE_NAME:
- case FLOAT_TYPE_NAME:
- case SMALLINT_TYPE_NAME:
- case TINYINT_TYPE_NAME:
- case DECIMAL_TYPE_NAME:
- case STRING_TYPE_NAME:
- // Pass an empty map or a map full of {null, null} will get
string type
- // An number in string format like "3.5" also support
- break;
- default:
+
+ this.mapOI = HiveUtils.asMapOI(argOIs[0]);
+ this.valueOI =
HiveUtils.asNumberOI(mapOI.getMapValueObjectInspector());
+
+ if (argOIs.length == 2) {
+ ObjectInspector argOI1 = argOIs[1];
+ if (HiveUtils.isIntegerOI(argOI1) == false) {
throw new UDFArgumentException(
- "Expected a number but get: " + valueOI.getTypeName());
+ "The second argument of map_roulette must be integer type:
"
+ + argOI1.getTypeName());
+ }
+ if (ObjectInspectorUtils.isConstantObjectInspector(argOI1)) {
+ long seed = HiveUtils.getAsConstLong(argOI1);
+ this._rand = new Random(seed); // fixed seed
+ } else {
+ this.seedOI = HiveUtils.asLongCompatibleOI(argOI1);
+ }
+ } else {
+ this._rand = new Random(); // random seed
}
- return keyOI;
+
+ return mapOI.getMapKeyObjectInspector();
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
- Map<Object, Double> input = processObjectDoubleMap(arguments[0]);
+ Random rand = _rand;
+ if (rand == null) {
+ Object arg1 = arguments[1].get();
+ if (arg1 == null) {
+ rand = new Random();
+ } else {
+ long seed = HiveUtils.getLong(arg1, seedOI);
+ rand = new Random(seed);
+ }
+ }
+
+ Map<Object, Double> input = getObjectDoubleMap(arguments[0], mapOI,
valueOI);
if (input == null) {
return null;
}
- return algorithm(input);
- }
- @Override
- public String getDisplayString(String[] children) {
- return "map_roulette(" + StringUtils.join(children, ',') + ")";
+ return rouletteWheelSelection(input, rand);
}
- /**
- * Process the data passed by user.
- *
- * @param argument data passed by user
- * @return If all the value is ,
- * @throws HiveException If get the wrong weight value like {key = "Wang",
value = "Zhang"},
- * "Zhang" isn't a number ,this Method will throw exception when
- * convertPrimitiveToDouble("Zhang", valueOD)
- */
- private Map<Object, Double> processObjectDoubleMap(DeferredObject argument)
- throws HiveException {
- // get
- Map<?, ?> m = mapOI.getMap(argument.get());
+ @Nullable
+ private static Map<Object, Double> getObjectDoubleMap(@Nonnull final
DeferredObject argument,
+ @Nonnull final MapObjectInspector mapOI,
+ @Nonnull final PrimitiveObjectInspector valueOI) throws
HiveException {
+ final Map<?, ?> m = mapOI.getMap(argument.get());
if (m == null) {
return null;
}
- if (m.size() == 0) {
+ final int size = m.size();
+ if (size == 0) {
return null;
}
- // convert
- Map<Object, Double> input = new HashMap<>();
- Double avg = 0.0;
+
+ final Map<Object, Double> result = new HashMap<>(size);
Review comment:
`Map<Object, Double> result` will be updated, why use final here?
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