com.datatorrent.lib.streamquery.OrderByRule 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;
import java.util.ArrayList;
import java.util.Map;
import java.util.TreeMap;
/**
* Implements order by key name rule.
*
* Properties :
* columnName : Name of column for ordering tuples.
* @displayName OrderBy Rule
* @category Stream Manipulators
* @tags orderby, sort, comparison
* @since 0.3.3
*/
@SuppressWarnings("rawtypes")
public class OrderByRule
{
/**
* column name for ordering tuples.
*/
private String columnName;
public OrderByRule(String name)
{
columnName = name;
}
/**
* sort rows by each rule and emit result on output port.
*/
@SuppressWarnings("unchecked")
public ArrayList> sort(ArrayList> rows)
{
TreeMap>> sorted = new TreeMap>>();
for (int i = 0; i < rows.size(); i++) {
Map row = rows.get(i);
if (row.containsKey(columnName)) {
T value = (T)row.get(columnName);
ArrayList> list;
if (sorted.containsKey(value)) {
list = sorted.get(value);
} else {
list = new ArrayList>();
sorted.put(value, list);
}
list.add(row);
}
}
ArrayList> result = new ArrayList>();
for (Map.Entry>> entry : sorted.entrySet()) {
result.addAll(entry.getValue());
}
return result;
}
/**
* @return the columnName
*/
public String getColumnName()
{
return columnName;
}
/**
* @param columnName
* the columnName to set
*/
public void setColumnName(String columnName)
{
this.columnName = columnName;
}
}