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| author | dwinter |
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| date | Tue, 04 Jan 2011 10:02:07 +0100 |
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<HTML> <BODY BGCOLOR="white"> <PRE> <FONT color="green">001</FONT> /*<a name="line.1"></a> <FONT color="green">002</FONT> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a> <FONT color="green">003</FONT> * contributor license agreements. See the NOTICE file distributed with<a name="line.3"></a> <FONT color="green">004</FONT> * this work for additional information regarding copyright ownership.<a name="line.4"></a> <FONT color="green">005</FONT> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a> <FONT color="green">006</FONT> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a> <FONT color="green">007</FONT> * the License. You may obtain a copy of the License at<a name="line.7"></a> <FONT color="green">008</FONT> *<a name="line.8"></a> <FONT color="green">009</FONT> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a> <FONT color="green">010</FONT> *<a name="line.10"></a> <FONT color="green">011</FONT> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a> <FONT color="green">012</FONT> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a> <FONT color="green">013</FONT> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a> <FONT color="green">014</FONT> * See the License for the specific language governing permissions and<a name="line.14"></a> <FONT color="green">015</FONT> * limitations under the License.<a name="line.15"></a> <FONT color="green">016</FONT> */<a name="line.16"></a> <FONT color="green">017</FONT> <a name="line.17"></a> <FONT color="green">018</FONT> package org.apache.commons.math.stat.descriptive;<a name="line.18"></a> <FONT color="green">019</FONT> <a name="line.19"></a> <FONT color="green">020</FONT> import java.io.Serializable;<a name="line.20"></a> <FONT color="green">021</FONT> import java.util.Collection;<a name="line.21"></a> <FONT color="green">022</FONT> import java.util.Iterator;<a name="line.22"></a> <FONT color="green">023</FONT> <a name="line.23"></a> <FONT color="green">024</FONT> /**<a name="line.24"></a> <FONT color="green">025</FONT> * <p><a name="line.25"></a> <FONT color="green">026</FONT> * An aggregator for {@code SummaryStatistics} from several data sets or<a name="line.26"></a> <FONT color="green">027</FONT> * data set partitions. In its simplest usage mode, the client creates an<a name="line.27"></a> <FONT color="green">028</FONT> * instance via the zero-argument constructor, then uses<a name="line.28"></a> <FONT color="green">029</FONT> * {@link #createContributingStatistics()} to obtain a {@code SummaryStatistics}<a name="line.29"></a> <FONT color="green">030</FONT> * for each individual data set / partition. The per-set statistics objects<a name="line.30"></a> <FONT color="green">031</FONT> * are used as normal, and at any time the aggregate statistics for all the<a name="line.31"></a> <FONT color="green">032</FONT> * contributors can be obtained from this object.<a name="line.32"></a> <FONT color="green">033</FONT> * </p><p><a name="line.33"></a> <FONT color="green">034</FONT> * Clients with specialized requirements can use alternative constructors to<a name="line.34"></a> <FONT color="green">035</FONT> * control the statistics implementations and initial values used by the<a name="line.35"></a> <FONT color="green">036</FONT> * contributing and the internal aggregate {@code SummaryStatistics} objects.<a name="line.36"></a> <FONT color="green">037</FONT> * </p><p><a name="line.37"></a> <FONT color="green">038</FONT> * A static {@link #aggregate(Collection)} method is also included that computes<a name="line.38"></a> <FONT color="green">039</FONT> * aggregate statistics directly from a Collection of SummaryStatistics instances.<a name="line.39"></a> <FONT color="green">040</FONT> * </p><p><a name="line.40"></a> <FONT color="green">041</FONT> * When {@link #createContributingStatistics()} is used to create SummaryStatistics<a name="line.41"></a> <FONT color="green">042</FONT> * instances to be aggregated concurrently, the created instances'<a name="line.42"></a> <FONT color="green">043</FONT> * {@link SummaryStatistics#addValue(double)} methods must synchronize on the aggregating<a name="line.43"></a> <FONT color="green">044</FONT> * instance maintained by this class. In multithreaded environments, if the functionality<a name="line.44"></a> <FONT color="green">045</FONT> * provided by {@link #aggregate(Collection)} is adequate, that method should be used<a name="line.45"></a> <FONT color="green">046</FONT> * to avoid unecessary computation and synchronization delays.</p><a name="line.46"></a> <FONT color="green">047</FONT> *<a name="line.47"></a> <FONT color="green">048</FONT> * @since 2.0<a name="line.48"></a> <FONT color="green">049</FONT> * @version $Revision: 811833 $ $Date: 2009-09-06 12:27:50 -0400 (Sun, 06 Sep 2009) $<a name="line.49"></a> <FONT color="green">050</FONT> *<a name="line.50"></a> <FONT color="green">051</FONT> */<a name="line.51"></a> <FONT color="green">052</FONT> public class AggregateSummaryStatistics implements StatisticalSummary,<a name="line.52"></a> <FONT color="green">053</FONT> Serializable {<a name="line.53"></a> <FONT color="green">054</FONT> <a name="line.54"></a> <FONT color="green">055</FONT> <a name="line.55"></a> <FONT color="green">056</FONT> /** Serializable version identifier */<a name="line.56"></a> <FONT color="green">057</FONT> private static final long serialVersionUID = -8207112444016386906L;<a name="line.57"></a> <FONT color="green">058</FONT> <a name="line.58"></a> <FONT color="green">059</FONT> /**<a name="line.59"></a> <FONT color="green">060</FONT> * A SummaryStatistics serving as a prototype for creating SummaryStatistics<a name="line.60"></a> <FONT color="green">061</FONT> * contributing to this aggregate<a name="line.61"></a> <FONT color="green">062</FONT> */<a name="line.62"></a> <FONT color="green">063</FONT> private final SummaryStatistics statisticsPrototype;<a name="line.63"></a> <FONT color="green">064</FONT> <a name="line.64"></a> <FONT color="green">065</FONT> /**<a name="line.65"></a> <FONT color="green">066</FONT> * The SummaryStatistics in which aggregate statistics are accumulated.<a name="line.66"></a> <FONT color="green">067</FONT> */<a name="line.67"></a> <FONT color="green">068</FONT> private final SummaryStatistics statistics;<a name="line.68"></a> <FONT color="green">069</FONT> <a name="line.69"></a> <FONT color="green">070</FONT> /**<a name="line.70"></a> <FONT color="green">071</FONT> * Initializes a new AggregateSummaryStatistics with default statistics<a name="line.71"></a> <FONT color="green">072</FONT> * implementations.<a name="line.72"></a> <FONT color="green">073</FONT> *<a name="line.73"></a> <FONT color="green">074</FONT> */<a name="line.74"></a> <FONT color="green">075</FONT> public AggregateSummaryStatistics() {<a name="line.75"></a> <FONT color="green">076</FONT> this(new SummaryStatistics());<a name="line.76"></a> <FONT color="green">077</FONT> }<a name="line.77"></a> <FONT color="green">078</FONT> <a name="line.78"></a> <FONT color="green">079</FONT> /**<a name="line.79"></a> <FONT color="green">080</FONT> * Initializes a new AggregateSummaryStatistics with the specified statistics<a name="line.80"></a> <FONT color="green">081</FONT> * object as a prototype for contributing statistics and for the internal<a name="line.81"></a> <FONT color="green">082</FONT> * aggregate statistics. This provides for customized statistics implementations<a name="line.82"></a> <FONT color="green">083</FONT> * to be used by contributing and aggregate statistics.<a name="line.83"></a> <FONT color="green">084</FONT> *<a name="line.84"></a> <FONT color="green">085</FONT> * @param prototypeStatistics a {@code SummaryStatistics} serving as a<a name="line.85"></a> <FONT color="green">086</FONT> * prototype both for the internal aggregate statistics and for<a name="line.86"></a> <FONT color="green">087</FONT> * contributing statistics obtained via the<a name="line.87"></a> <FONT color="green">088</FONT> * {@code createContributingStatistics()} method. Being a prototype<a name="line.88"></a> <FONT color="green">089</FONT> * means that other objects are initialized by copying this object's state.<a name="line.89"></a> <FONT color="green">090</FONT> * If {@code null}, a new, default statistics object is used. Any statistic<a name="line.90"></a> <FONT color="green">091</FONT> * values in the prototype are propagated to contributing statistics<a name="line.91"></a> <FONT color="green">092</FONT> * objects and (once) into these aggregate statistics.<a name="line.92"></a> <FONT color="green">093</FONT> * @see #createContributingStatistics()<a name="line.93"></a> <FONT color="green">094</FONT> */<a name="line.94"></a> <FONT color="green">095</FONT> public AggregateSummaryStatistics(SummaryStatistics prototypeStatistics) {<a name="line.95"></a> <FONT color="green">096</FONT> this(prototypeStatistics,<a name="line.96"></a> <FONT color="green">097</FONT> prototypeStatistics == null ? null : new SummaryStatistics(prototypeStatistics));<a name="line.97"></a> <FONT color="green">098</FONT> }<a name="line.98"></a> <FONT color="green">099</FONT> <a name="line.99"></a> <FONT color="green">100</FONT> /**<a name="line.100"></a> <FONT color="green">101</FONT> * Initializes a new AggregateSummaryStatistics with the specified statistics<a name="line.101"></a> <FONT color="green">102</FONT> * object as a prototype for contributing statistics and for the internal<a name="line.102"></a> <FONT color="green">103</FONT> * aggregate statistics. This provides for different statistics implementations<a name="line.103"></a> <FONT color="green">104</FONT> * to be used by contributing and aggregate statistics and for an initial<a name="line.104"></a> <FONT color="green">105</FONT> * state to be supplied for the aggregate statistics.<a name="line.105"></a> <FONT color="green">106</FONT> *<a name="line.106"></a> <FONT color="green">107</FONT> * @param prototypeStatistics a {@code SummaryStatistics} serving as a<a name="line.107"></a> <FONT color="green">108</FONT> * prototype both for the internal aggregate statistics and for<a name="line.108"></a> <FONT color="green">109</FONT> * contributing statistics obtained via the<a name="line.109"></a> <FONT color="green">110</FONT> * {@code createContributingStatistics()} method. Being a prototype<a name="line.110"></a> <FONT color="green">111</FONT> * means that other objects are initialized by copying this object's state.<a name="line.111"></a> <FONT color="green">112</FONT> * If {@code null}, a new, default statistics object is used. Any statistic<a name="line.112"></a> <FONT color="green">113</FONT> * values in the prototype are propagated to contributing statistics<a name="line.113"></a> <FONT color="green">114</FONT> * objects, but not into these aggregate statistics.<a name="line.114"></a> <FONT color="green">115</FONT> * @param initialStatistics a {@code SummaryStatistics} to serve as the<a name="line.115"></a> <FONT color="green">116</FONT> * internal aggregate statistics object. If {@code null}, a new, default<a name="line.116"></a> <FONT color="green">117</FONT> * statistics object is used.<a name="line.117"></a> <FONT color="green">118</FONT> * @see #createContributingStatistics()<a name="line.118"></a> <FONT color="green">119</FONT> */<a name="line.119"></a> <FONT color="green">120</FONT> public AggregateSummaryStatistics(SummaryStatistics prototypeStatistics,<a name="line.120"></a> <FONT color="green">121</FONT> SummaryStatistics initialStatistics) {<a name="line.121"></a> <FONT color="green">122</FONT> this.statisticsPrototype =<a name="line.122"></a> <FONT color="green">123</FONT> (prototypeStatistics == null) ? new SummaryStatistics() : prototypeStatistics;<a name="line.123"></a> <FONT color="green">124</FONT> this.statistics =<a name="line.124"></a> <FONT color="green">125</FONT> (initialStatistics == null) ? new SummaryStatistics() : initialStatistics;<a name="line.125"></a> <FONT color="green">126</FONT> }<a name="line.126"></a> <FONT color="green">127</FONT> <a name="line.127"></a> <FONT color="green">128</FONT> /**<a name="line.128"></a> <FONT color="green">129</FONT> * {@inheritDoc}. This version returns the maximum over all the aggregated<a name="line.129"></a> <FONT color="green">130</FONT> * data.<a name="line.130"></a> <FONT color="green">131</FONT> *<a name="line.131"></a> <FONT color="green">132</FONT> * @see StatisticalSummary#getMax()<a name="line.132"></a> <FONT color="green">133</FONT> */<a name="line.133"></a> <FONT color="green">134</FONT> public double getMax() {<a name="line.134"></a> <FONT color="green">135</FONT> synchronized (statistics) {<a name="line.135"></a> <FONT color="green">136</FONT> return statistics.getMax();<a name="line.136"></a> <FONT color="green">137</FONT> }<a name="line.137"></a> <FONT color="green">138</FONT> }<a name="line.138"></a> <FONT color="green">139</FONT> <a name="line.139"></a> <FONT color="green">140</FONT> /**<a name="line.140"></a> <FONT color="green">141</FONT> * {@inheritDoc}. This version returns the mean of all the aggregated data.<a name="line.141"></a> <FONT color="green">142</FONT> *<a name="line.142"></a> <FONT color="green">143</FONT> * @see StatisticalSummary#getMean()<a name="line.143"></a> <FONT color="green">144</FONT> */<a name="line.144"></a> <FONT color="green">145</FONT> public double getMean() {<a name="line.145"></a> <FONT color="green">146</FONT> synchronized (statistics) {<a name="line.146"></a> <FONT color="green">147</FONT> return statistics.getMean();<a name="line.147"></a> <FONT color="green">148</FONT> }<a name="line.148"></a> <FONT color="green">149</FONT> }<a name="line.149"></a> <FONT color="green">150</FONT> <a name="line.150"></a> <FONT color="green">151</FONT> /**<a name="line.151"></a> <FONT color="green">152</FONT> * {@inheritDoc}. This version returns the minimum over all the aggregated<a name="line.152"></a> <FONT color="green">153</FONT> * data.<a name="line.153"></a> <FONT color="green">154</FONT> *<a name="line.154"></a> <FONT color="green">155</FONT> * @see StatisticalSummary#getMin()<a name="line.155"></a> <FONT color="green">156</FONT> */<a name="line.156"></a> <FONT color="green">157</FONT> public double getMin() {<a name="line.157"></a> <FONT color="green">158</FONT> synchronized (statistics) {<a name="line.158"></a> <FONT color="green">159</FONT> return statistics.getMin();<a name="line.159"></a> <FONT color="green">160</FONT> }<a name="line.160"></a> <FONT color="green">161</FONT> }<a name="line.161"></a> <FONT color="green">162</FONT> <a name="line.162"></a> <FONT color="green">163</FONT> /**<a name="line.163"></a> <FONT color="green">164</FONT> * {@inheritDoc}. This version returns a count of all the aggregated data.<a name="line.164"></a> <FONT color="green">165</FONT> *<a name="line.165"></a> <FONT color="green">166</FONT> * @see StatisticalSummary#getN()<a name="line.166"></a> <FONT color="green">167</FONT> */<a name="line.167"></a> <FONT color="green">168</FONT> public long getN() {<a name="line.168"></a> <FONT color="green">169</FONT> synchronized (statistics) {<a name="line.169"></a> <FONT color="green">170</FONT> return statistics.getN();<a name="line.170"></a> <FONT color="green">171</FONT> }<a name="line.171"></a> <FONT color="green">172</FONT> }<a name="line.172"></a> <FONT color="green">173</FONT> <a name="line.173"></a> <FONT color="green">174</FONT> /**<a name="line.174"></a> <FONT color="green">175</FONT> * {@inheritDoc}. This version returns the standard deviation of all the<a name="line.175"></a> <FONT color="green">176</FONT> * aggregated data.<a name="line.176"></a> <FONT color="green">177</FONT> *<a name="line.177"></a> <FONT color="green">178</FONT> * @see StatisticalSummary#getStandardDeviation()<a name="line.178"></a> <FONT color="green">179</FONT> */<a name="line.179"></a> <FONT color="green">180</FONT> public double getStandardDeviation() {<a name="line.180"></a> <FONT color="green">181</FONT> synchronized (statistics) {<a name="line.181"></a> <FONT color="green">182</FONT> return statistics.getStandardDeviation();<a name="line.182"></a> <FONT color="green">183</FONT> }<a name="line.183"></a> <FONT color="green">184</FONT> }<a name="line.184"></a> <FONT color="green">185</FONT> <a name="line.185"></a> <FONT color="green">186</FONT> /**<a name="line.186"></a> <FONT color="green">187</FONT> * {@inheritDoc}. This version returns a sum of all the aggregated data.<a name="line.187"></a> <FONT color="green">188</FONT> *<a name="line.188"></a> <FONT color="green">189</FONT> * @see StatisticalSummary#getSum()<a name="line.189"></a> <FONT color="green">190</FONT> */<a name="line.190"></a> <FONT color="green">191</FONT> public double getSum() {<a name="line.191"></a> <FONT color="green">192</FONT> synchronized (statistics) {<a name="line.192"></a> <FONT color="green">193</FONT> return statistics.getSum();<a name="line.193"></a> <FONT color="green">194</FONT> }<a name="line.194"></a> <FONT color="green">195</FONT> }<a name="line.195"></a> <FONT color="green">196</FONT> <a name="line.196"></a> <FONT color="green">197</FONT> /**<a name="line.197"></a> <FONT color="green">198</FONT> * {@inheritDoc}. This version returns the variance of all the aggregated<a name="line.198"></a> <FONT color="green">199</FONT> * data.<a name="line.199"></a> <FONT color="green">200</FONT> *<a name="line.200"></a> <FONT color="green">201</FONT> * @see StatisticalSummary#getVariance()<a name="line.201"></a> <FONT color="green">202</FONT> */<a name="line.202"></a> <FONT color="green">203</FONT> public double getVariance() {<a name="line.203"></a> <FONT color="green">204</FONT> synchronized (statistics) {<a name="line.204"></a> <FONT color="green">205</FONT> return statistics.getVariance();<a name="line.205"></a> <FONT color="green">206</FONT> }<a name="line.206"></a> <FONT color="green">207</FONT> }<a name="line.207"></a> <FONT color="green">208</FONT> <a name="line.208"></a> <FONT color="green">209</FONT> /**<a name="line.209"></a> <FONT color="green">210</FONT> * Returns the sum of the logs of all the aggregated data.<a name="line.210"></a> <FONT color="green">211</FONT> *<a name="line.211"></a> <FONT color="green">212</FONT> * @return the sum of logs<a name="line.212"></a> <FONT color="green">213</FONT> * @see SummaryStatistics#getSumOfLogs()<a name="line.213"></a> <FONT color="green">214</FONT> */<a name="line.214"></a> <FONT color="green">215</FONT> public double getSumOfLogs() {<a name="line.215"></a> <FONT color="green">216</FONT> synchronized (statistics) {<a name="line.216"></a> <FONT color="green">217</FONT> return statistics.getSumOfLogs();<a name="line.217"></a> <FONT color="green">218</FONT> }<a name="line.218"></a> <FONT color="green">219</FONT> }<a name="line.219"></a> <FONT color="green">220</FONT> <a name="line.220"></a> <FONT color="green">221</FONT> /**<a name="line.221"></a> <FONT color="green">222</FONT> * Returns the geometric mean of all the aggregated data.<a name="line.222"></a> <FONT color="green">223</FONT> *<a name="line.223"></a> <FONT color="green">224</FONT> * @return the geometric mean<a name="line.224"></a> <FONT color="green">225</FONT> * @see SummaryStatistics#getGeometricMean()<a name="line.225"></a> <FONT color="green">226</FONT> */<a name="line.226"></a> <FONT color="green">227</FONT> public double getGeometricMean() {<a name="line.227"></a> <FONT color="green">228</FONT> synchronized (statistics) {<a name="line.228"></a> <FONT color="green">229</FONT> return statistics.getGeometricMean();<a name="line.229"></a> <FONT color="green">230</FONT> }<a name="line.230"></a> <FONT color="green">231</FONT> }<a name="line.231"></a> <FONT color="green">232</FONT> <a name="line.232"></a> <FONT color="green">233</FONT> /**<a name="line.233"></a> <FONT color="green">234</FONT> * Returns the sum of the squares of all the aggregated data.<a name="line.234"></a> <FONT color="green">235</FONT> *<a name="line.235"></a> <FONT color="green">236</FONT> * @return The sum of squares<a name="line.236"></a> <FONT color="green">237</FONT> * @see SummaryStatistics#getSumsq()<a name="line.237"></a> <FONT color="green">238</FONT> */<a name="line.238"></a> <FONT color="green">239</FONT> public double getSumsq() {<a name="line.239"></a> <FONT color="green">240</FONT> synchronized (statistics) {<a name="line.240"></a> <FONT color="green">241</FONT> return statistics.getSumsq();<a name="line.241"></a> <FONT color="green">242</FONT> }<a name="line.242"></a> <FONT color="green">243</FONT> }<a name="line.243"></a> <FONT color="green">244</FONT> <a name="line.244"></a> <FONT color="green">245</FONT> /**<a name="line.245"></a> <FONT color="green">246</FONT> * Returns a statistic related to the Second Central Moment. Specifically,<a name="line.246"></a> <FONT color="green">247</FONT> * what is returned is the sum of squared deviations from the sample mean<a name="line.247"></a> <FONT color="green">248</FONT> * among the all of the aggregated data.<a name="line.248"></a> <FONT color="green">249</FONT> *<a name="line.249"></a> <FONT color="green">250</FONT> * @return second central moment statistic<a name="line.250"></a> <FONT color="green">251</FONT> * @see SummaryStatistics#getSecondMoment()<a name="line.251"></a> <FONT color="green">252</FONT> */<a name="line.252"></a> <FONT color="green">253</FONT> public double getSecondMoment() {<a name="line.253"></a> <FONT color="green">254</FONT> synchronized (statistics) {<a name="line.254"></a> <FONT color="green">255</FONT> return statistics.getSecondMoment();<a name="line.255"></a> <FONT color="green">256</FONT> }<a name="line.256"></a> <FONT color="green">257</FONT> }<a name="line.257"></a> <FONT color="green">258</FONT> <a name="line.258"></a> <FONT color="green">259</FONT> /**<a name="line.259"></a> <FONT color="green">260</FONT> * Return a {@link StatisticalSummaryValues} instance reporting current<a name="line.260"></a> <FONT color="green">261</FONT> * aggregate statistics.<a name="line.261"></a> <FONT color="green">262</FONT> *<a name="line.262"></a> <FONT color="green">263</FONT> * @return Current values of aggregate statistics<a name="line.263"></a> <FONT color="green">264</FONT> */<a name="line.264"></a> <FONT color="green">265</FONT> public StatisticalSummary getSummary() {<a name="line.265"></a> <FONT color="green">266</FONT> synchronized (statistics) {<a name="line.266"></a> <FONT color="green">267</FONT> return new StatisticalSummaryValues(getMean(), getVariance(), getN(),<a name="line.267"></a> <FONT color="green">268</FONT> getMax(), getMin(), getSum());<a name="line.268"></a> <FONT color="green">269</FONT> }<a name="line.269"></a> <FONT color="green">270</FONT> }<a name="line.270"></a> <FONT color="green">271</FONT> <a name="line.271"></a> <FONT color="green">272</FONT> /**<a name="line.272"></a> <FONT color="green">273</FONT> * Creates and returns a {@code SummaryStatistics} whose data will be<a name="line.273"></a> <FONT color="green">274</FONT> * aggregated with those of this {@code AggregateSummaryStatistics}.<a name="line.274"></a> <FONT color="green">275</FONT> *<a name="line.275"></a> <FONT color="green">276</FONT> * @return a {@code SummaryStatistics} whose data will be aggregated with<a name="line.276"></a> <FONT color="green">277</FONT> * those of this {@code AggregateSummaryStatistics}. The initial state<a name="line.277"></a> <FONT color="green">278</FONT> * is a copy of the configured prototype statistics.<a name="line.278"></a> <FONT color="green">279</FONT> */<a name="line.279"></a> <FONT color="green">280</FONT> public SummaryStatistics createContributingStatistics() {<a name="line.280"></a> <FONT color="green">281</FONT> SummaryStatistics contributingStatistics<a name="line.281"></a> <FONT color="green">282</FONT> = new AggregatingSummaryStatistics(statistics);<a name="line.282"></a> <FONT color="green">283</FONT> <a name="line.283"></a> <FONT color="green">284</FONT> SummaryStatistics.copy(statisticsPrototype, contributingStatistics);<a name="line.284"></a> <FONT color="green">285</FONT> <a name="line.285"></a> <FONT color="green">286</FONT> return contributingStatistics;<a name="line.286"></a> <FONT color="green">287</FONT> }<a name="line.287"></a> <FONT color="green">288</FONT> <a name="line.288"></a> <FONT color="green">289</FONT> /**<a name="line.289"></a> <FONT color="green">290</FONT> * Computes aggregate summary statistics. This method can be used to combine statistics<a name="line.290"></a> <FONT color="green">291</FONT> * computed over partitions or subsamples - i.e., the StatisticalSummaryValues returned<a name="line.291"></a> <FONT color="green">292</FONT> * should contain the same values that would have been obtained by computing a single<a name="line.292"></a> <FONT color="green">293</FONT> * StatisticalSummary over the combined dataset.<a name="line.293"></a> <FONT color="green">294</FONT> * <p><a name="line.294"></a> <FONT color="green">295</FONT> * Returns null if the collection is empty or null.<a name="line.295"></a> <FONT color="green">296</FONT> * </p><a name="line.296"></a> <FONT color="green">297</FONT> *<a name="line.297"></a> <FONT color="green">298</FONT> * @param statistics collection of SummaryStatistics to aggregate<a name="line.298"></a> <FONT color="green">299</FONT> * @return summary statistics for the combined dataset<a name="line.299"></a> <FONT color="green">300</FONT> */<a name="line.300"></a> <FONT color="green">301</FONT> public static StatisticalSummaryValues aggregate(Collection<SummaryStatistics> statistics) {<a name="line.301"></a> <FONT color="green">302</FONT> if (statistics == null) {<a name="line.302"></a> <FONT color="green">303</FONT> return null;<a name="line.303"></a> <FONT color="green">304</FONT> }<a name="line.304"></a> <FONT color="green">305</FONT> Iterator<SummaryStatistics> iterator = statistics.iterator();<a name="line.305"></a> <FONT color="green">306</FONT> if (!iterator.hasNext()) {<a name="line.306"></a> <FONT color="green">307</FONT> return null;<a name="line.307"></a> <FONT color="green">308</FONT> }<a name="line.308"></a> <FONT color="green">309</FONT> SummaryStatistics current = iterator.next();<a name="line.309"></a> <FONT color="green">310</FONT> long n = current.getN();<a name="line.310"></a> <FONT color="green">311</FONT> double min = current.getMin();<a name="line.311"></a> <FONT color="green">312</FONT> double sum = current.getSum();<a name="line.312"></a> <FONT color="green">313</FONT> double max = current.getMax();<a name="line.313"></a> <FONT color="green">314</FONT> double m2 = current.getSecondMoment();<a name="line.314"></a> <FONT color="green">315</FONT> double mean = current.getMean();<a name="line.315"></a> <FONT color="green">316</FONT> while (iterator.hasNext()) {<a name="line.316"></a> <FONT color="green">317</FONT> current = iterator.next();<a name="line.317"></a> <FONT color="green">318</FONT> if (current.getMin() < min || Double.isNaN(min)) {<a name="line.318"></a> <FONT color="green">319</FONT> min = current.getMin();<a name="line.319"></a> <FONT color="green">320</FONT> }<a name="line.320"></a> <FONT color="green">321</FONT> if (current.getMax() > max || Double.isNaN(max)) {<a name="line.321"></a> <FONT color="green">322</FONT> max = current.getMax();<a name="line.322"></a> <FONT color="green">323</FONT> }<a name="line.323"></a> <FONT color="green">324</FONT> sum += current.getSum();<a name="line.324"></a> <FONT color="green">325</FONT> final double oldN = n;<a name="line.325"></a> <FONT color="green">326</FONT> final double curN = current.getN();<a name="line.326"></a> <FONT color="green">327</FONT> n += curN;<a name="line.327"></a> <FONT color="green">328</FONT> final double meanDiff = current.getMean() - mean;<a name="line.328"></a> <FONT color="green">329</FONT> mean = sum / n;<a name="line.329"></a> <FONT color="green">330</FONT> m2 = m2 + current.getSecondMoment() + meanDiff * meanDiff * oldN * curN / n;<a name="line.330"></a> <FONT color="green">331</FONT> }<a name="line.331"></a> <FONT color="green">332</FONT> final double variance;<a name="line.332"></a> <FONT color="green">333</FONT> if (n == 0) {<a name="line.333"></a> <FONT color="green">334</FONT> variance = Double.NaN;<a name="line.334"></a> <FONT color="green">335</FONT> } else if (n == 1) {<a name="line.335"></a> <FONT color="green">336</FONT> variance = 0d;<a name="line.336"></a> <FONT color="green">337</FONT> } else {<a name="line.337"></a> <FONT color="green">338</FONT> variance = m2 / (n - 1);<a name="line.338"></a> <FONT color="green">339</FONT> }<a name="line.339"></a> <FONT color="green">340</FONT> return new StatisticalSummaryValues(mean, variance, n, max, min, sum);<a name="line.340"></a> <FONT color="green">341</FONT> }<a name="line.341"></a> <FONT color="green">342</FONT> <a name="line.342"></a> <FONT color="green">343</FONT> /**<a name="line.343"></a> <FONT color="green">344</FONT> * A SummaryStatistics that also forwards all values added to it to a second<a name="line.344"></a> <FONT color="green">345</FONT> * {@code SummaryStatistics} for aggregation.<a name="line.345"></a> <FONT color="green">346</FONT> *<a name="line.346"></a> <FONT color="green">347</FONT> * @since 2.0<a name="line.347"></a> <FONT color="green">348</FONT> */<a name="line.348"></a> <FONT color="green">349</FONT> private static class AggregatingSummaryStatistics extends SummaryStatistics {<a name="line.349"></a> <FONT color="green">350</FONT> <a name="line.350"></a> <FONT color="green">351</FONT> /**<a name="line.351"></a> <FONT color="green">352</FONT> * The serialization version of this class<a name="line.352"></a> <FONT color="green">353</FONT> */<a name="line.353"></a> <FONT color="green">354</FONT> private static final long serialVersionUID = 1L;<a name="line.354"></a> <FONT color="green">355</FONT> <a name="line.355"></a> <FONT color="green">356</FONT> /**<a name="line.356"></a> <FONT color="green">357</FONT> * An additional SummaryStatistics into which values added to these<a name="line.357"></a> <FONT color="green">358</FONT> * statistics (and possibly others) are aggregated<a name="line.358"></a> <FONT color="green">359</FONT> */<a name="line.359"></a> <FONT color="green">360</FONT> private final SummaryStatistics aggregateStatistics;<a name="line.360"></a> <FONT color="green">361</FONT> <a name="line.361"></a> <FONT color="green">362</FONT> /**<a name="line.362"></a> <FONT color="green">363</FONT> * Initializes a new AggregatingSummaryStatistics with the specified<a name="line.363"></a> <FONT color="green">364</FONT> * aggregate statistics object<a name="line.364"></a> <FONT color="green">365</FONT> *<a name="line.365"></a> <FONT color="green">366</FONT> * @param aggregateStatistics a {@code SummaryStatistics} into which<a name="line.366"></a> <FONT color="green">367</FONT> * values added to this statistics object should be aggregated<a name="line.367"></a> <FONT color="green">368</FONT> */<a name="line.368"></a> <FONT color="green">369</FONT> public AggregatingSummaryStatistics(SummaryStatistics aggregateStatistics) {<a name="line.369"></a> <FONT color="green">370</FONT> this.aggregateStatistics = aggregateStatistics;<a name="line.370"></a> <FONT color="green">371</FONT> }<a name="line.371"></a> <FONT color="green">372</FONT> <a name="line.372"></a> <FONT color="green">373</FONT> /**<a name="line.373"></a> <FONT color="green">374</FONT> * {@inheritDoc}. This version adds the provided value to the configured<a name="line.374"></a> <FONT color="green">375</FONT> * aggregate after adding it to these statistics.<a name="line.375"></a> <FONT color="green">376</FONT> *<a name="line.376"></a> <FONT color="green">377</FONT> * @see SummaryStatistics#addValue(double)<a name="line.377"></a> <FONT color="green">378</FONT> */<a name="line.378"></a> <FONT color="green">379</FONT> @Override<a name="line.379"></a> <FONT color="green">380</FONT> public void addValue(double value) {<a name="line.380"></a> <FONT color="green">381</FONT> super.addValue(value);<a name="line.381"></a> <FONT color="green">382</FONT> synchronized (aggregateStatistics) {<a name="line.382"></a> <FONT color="green">383</FONT> aggregateStatistics.addValue(value);<a name="line.383"></a> <FONT color="green">384</FONT> }<a name="line.384"></a> <FONT color="green">385</FONT> }<a name="line.385"></a> <FONT color="green">386</FONT> <a name="line.386"></a> <FONT color="green">387</FONT> /**<a name="line.387"></a> <FONT color="green">388</FONT> * Returns true iff <code>object</code> is a<a name="line.388"></a> <FONT color="green">389</FONT> * <code>SummaryStatistics</code> instance and all statistics have the<a name="line.389"></a> <FONT color="green">390</FONT> * same values as this.<a name="line.390"></a> <FONT color="green">391</FONT> * @param object the object to test equality against.<a name="line.391"></a> <FONT color="green">392</FONT> * @return true if object equals this<a name="line.392"></a> <FONT color="green">393</FONT> */<a name="line.393"></a> <FONT color="green">394</FONT> @Override<a name="line.394"></a> <FONT color="green">395</FONT> public boolean equals(Object object) {<a name="line.395"></a> <FONT color="green">396</FONT> if (object == this) {<a name="line.396"></a> <FONT color="green">397</FONT> return true;<a name="line.397"></a> <FONT color="green">398</FONT> }<a name="line.398"></a> <FONT color="green">399</FONT> if (object instanceof AggregatingSummaryStatistics == false) {<a name="line.399"></a> <FONT color="green">400</FONT> return false;<a name="line.400"></a> <FONT color="green">401</FONT> }<a name="line.401"></a> <FONT color="green">402</FONT> AggregatingSummaryStatistics stat = (AggregatingSummaryStatistics)object;<a name="line.402"></a> <FONT color="green">403</FONT> return super.equals(stat) &&<a name="line.403"></a> <FONT color="green">404</FONT> aggregateStatistics.equals(stat.aggregateStatistics);<a name="line.404"></a> <FONT color="green">405</FONT> }<a name="line.405"></a> <FONT color="green">406</FONT> <a name="line.406"></a> <FONT color="green">407</FONT> /**<a name="line.407"></a> <FONT color="green">408</FONT> * Returns hash code based on values of statistics<a name="line.408"></a> <FONT color="green">409</FONT> * @return hash code<a name="line.409"></a> <FONT color="green">410</FONT> */<a name="line.410"></a> <FONT color="green">411</FONT> @Override<a name="line.411"></a> <FONT color="green">412</FONT> public int hashCode() {<a name="line.412"></a> <FONT color="green">413</FONT> return 123 + super.hashCode() + aggregateStatistics.hashCode();<a name="line.413"></a> <FONT color="green">414</FONT> }<a name="line.414"></a> <FONT color="green">415</FONT> }<a name="line.415"></a> <FONT color="green">416</FONT> }<a name="line.416"></a> </PRE> </BODY> </HTML>