/*
* Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
* license agreements. See the NOTICE file distributed with this work for
* additional information regarding copyright ownership. Crate 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.
*
* However, if you have executed another commercial license agreement
* with Crate these terms will supersede the license and you may use the
* software solely pursuant to the terms of the relevant commercial agreement.
*/
package io.crate.operation.scalar;
import com.google.common.collect.ImmutableList;
import io.crate.metadata.FunctionIdent;
import io.crate.metadata.FunctionInfo;
import io.crate.metadata.Scalar;
import io.crate.operation.Input;
import io.crate.planner.symbol.Function;
import io.crate.planner.symbol.Symbol;
import io.crate.types.DataType;
import io.crate.types.DataTypes;
import io.crate.types.SetType;
import java.util.Set;
public class CollectionAverageFunction extends Scalar<Double, Set<Number>> {
public static final String NAME = "collection_avg";
private final FunctionInfo info;
public static void register(ScalarFunctionModule mod) {
for (DataType t : DataTypes.NUMERIC_PRIMITIVE_TYPES) {
mod.register(
new CollectionAverageFunction(
new FunctionInfo(new FunctionIdent(
NAME, ImmutableList.<DataType>of(new SetType(t))), DataTypes.DOUBLE))
);
}
}
public CollectionAverageFunction(FunctionInfo info) {
this.info = info;
}
@Override
public Double evaluate(Input<Set<Number>>... args) {
// NOTE: always returning double ignoring the input type, maybe better implement type safe
if (args[0].value() == null) {
return null;
}
double sum = 0;
long count = 0;
for (Number value : args[0].value()) {
sum += value.doubleValue();
count++;
}
if (count > 0) {
return sum / count;
} else {
return null;
}
}
@Override
public FunctionInfo info() {
return info;
}
@Override
public Symbol normalizeSymbol(Function function) {
return function;
}
}