com.datatorrent.lib.streamquery.index.SumExpression Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.
*/
package com.datatorrent.lib.streamquery.index;
import java.util.Map;
import javax.validation.constraints.NotNull;
/**
* Implements sum on column index.
*
* Select index class for implementing sum column index.
* @displayName Sum Expression
* @category Stream Manipulators
* @tags sum
* @since 0.3.4
*/
public class SumExpression extends BinaryExpression
{
/**
* @param left column name argument for expression.
* @param right column name argument for expression.
* @param alias name for output field.
*/
public SumExpression(@NotNull String left, @NotNull String right, String alias)
{
super(left, right, alias);
if (this.alias == null) {
this.alias = "SUM(" + left + "," + right + ")";
}
}
/* sum column values.
* @see com.datatorrent.lib.streamquery.index.Index#filter(java.util.Map, java.util.Map)
*/
@Override
public void filter(Map row, Map collect)
{
if (!row.containsKey(left) || !row.containsKey(right)) {
return;
}
collect.put(alias, ((Number)row.get(left)).doubleValue() + ((Number)row.get(right)).doubleValue());
}
}