statistics.html

jfreechart1。0。2的api。

<FONT color="green">316</FONT>    <a name="line.316"></a>
<FONT color="green">317</FONT>        }<a name="line.317"></a>
<FONT color="green">318</FONT>    <a name="line.318"></a>
<FONT color="green">319</FONT>        /**<a name="line.319"></a>
<FONT color="green">320</FONT>         * Calculates the correlation between two datasets.  Both arrays should <a name="line.320"></a>
<FONT color="green">321</FONT>         * contain the same number of items.  Null values are treated as zero.<a name="line.321"></a>
<FONT color="green">322</FONT>         * &lt;P&gt;<a name="line.322"></a>
<FONT color="green">323</FONT>         * Information about the correlation calculation was obtained from:<a name="line.323"></a>
<FONT color="green">324</FONT>         * <a name="line.324"></a>
<FONT color="green">325</FONT>         * http://trochim.human.cornell.edu/kb/statcorr.htm<a name="line.325"></a>
<FONT color="green">326</FONT>         * <a name="line.326"></a>
<FONT color="green">327</FONT>         * @param data1  the first dataset.<a name="line.327"></a>
<FONT color="green">328</FONT>         * @param data2  the second dataset.<a name="line.328"></a>
<FONT color="green">329</FONT>         * <a name="line.329"></a>
<FONT color="green">330</FONT>         * @return The correlation.<a name="line.330"></a>
<FONT color="green">331</FONT>         */<a name="line.331"></a>
<FONT color="green">332</FONT>        public static double getCorrelation(Number[] data1, Number[] data2) {<a name="line.332"></a>
<FONT color="green">333</FONT>            if (data1 == null) {<a name="line.333"></a>
<FONT color="green">334</FONT>                throw new IllegalArgumentException("Null 'data1' argument.");<a name="line.334"></a>
<FONT color="green">335</FONT>            }<a name="line.335"></a>
<FONT color="green">336</FONT>            if (data2 == null) {<a name="line.336"></a>
<FONT color="green">337</FONT>                throw new IllegalArgumentException("Null 'data2' argument.");<a name="line.337"></a>
<FONT color="green">338</FONT>            }<a name="line.338"></a>
<FONT color="green">339</FONT>            if (data1.length != data2.length) {<a name="line.339"></a>
<FONT color="green">340</FONT>                throw new IllegalArgumentException(<a name="line.340"></a>
<FONT color="green">341</FONT>                    "'data1' and 'data2' arrays must have same length."<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>            int n = data1.length;<a name="line.344"></a>
<FONT color="green">345</FONT>            double sumX = 0.0;<a name="line.345"></a>
<FONT color="green">346</FONT>            double sumY = 0.0;<a name="line.346"></a>
<FONT color="green">347</FONT>            double sumX2 = 0.0;<a name="line.347"></a>
<FONT color="green">348</FONT>            double sumY2 = 0.0;<a name="line.348"></a>
<FONT color="green">349</FONT>            double sumXY = 0.0;<a name="line.349"></a>
<FONT color="green">350</FONT>            for (int i = 0; i &lt; n; i++) {<a name="line.350"></a>
<FONT color="green">351</FONT>                double x = 0.0;<a name="line.351"></a>
<FONT color="green">352</FONT>                if (data1[i] != null) {<a name="line.352"></a>
<FONT color="green">353</FONT>                    x = data1[i].doubleValue();   <a name="line.353"></a>
<FONT color="green">354</FONT>                }<a name="line.354"></a>
<FONT color="green">355</FONT>                double y = 0.0;<a name="line.355"></a>
<FONT color="green">356</FONT>                if (data2[i] != null) {<a name="line.356"></a>
<FONT color="green">357</FONT>                    y = data2[i].doubleValue();   <a name="line.357"></a>
<FONT color="green">358</FONT>                }<a name="line.358"></a>
<FONT color="green">359</FONT>                sumX = sumX + x;<a name="line.359"></a>
<FONT color="green">360</FONT>                sumY = sumY + y;<a name="line.360"></a>
<FONT color="green">361</FONT>                sumXY = sumXY + (x * y);<a name="line.361"></a>
<FONT color="green">362</FONT>                sumX2 = sumX2 + (x * x);<a name="line.362"></a>
<FONT color="green">363</FONT>                sumY2 = sumY2 + (y * y);<a name="line.363"></a>
<FONT color="green">364</FONT>            }<a name="line.364"></a>
<FONT color="green">365</FONT>            return (n * sumXY - sumX * sumY) / Math.pow((n * sumX2 - sumX * sumX) <a name="line.365"></a>
<FONT color="green">366</FONT>                    * (n * sumY2 - sumY * sumY), 0.5);      <a name="line.366"></a>
<FONT color="green">367</FONT>        }<a name="line.367"></a>
<FONT color="green">368</FONT>    <a name="line.368"></a>
<FONT color="green">369</FONT>        /**<a name="line.369"></a>
<FONT color="green">370</FONT>         * Returns a data set for a moving average on the data set passed in.<a name="line.370"></a>
<FONT color="green">371</FONT>         *<a name="line.371"></a>
<FONT color="green">372</FONT>         * @param xData  an array of the x data.<a name="line.372"></a>
<FONT color="green">373</FONT>         * @param yData  an array of the y data.<a name="line.373"></a>
<FONT color="green">374</FONT>         * @param period  the number of data points to average<a name="line.374"></a>
<FONT color="green">375</FONT>         *<a name="line.375"></a>
<FONT color="green">376</FONT>         * @return A double[][] the length of the data set in the first dimension,<a name="line.376"></a>
<FONT color="green">377</FONT>         *         with two doubles for x and y in the second dimension<a name="line.377"></a>
<FONT color="green">378</FONT>         */<a name="line.378"></a>
<FONT color="green">379</FONT>        public static double[][] getMovingAverage(Number[] xData, <a name="line.379"></a>
<FONT color="green">380</FONT>                                                  Number[] yData, <a name="line.380"></a>
<FONT color="green">381</FONT>                                                  int period) {<a name="line.381"></a>
<FONT color="green">382</FONT>    <a name="line.382"></a>
<FONT color="green">383</FONT>            // check arguments...<a name="line.383"></a>
<FONT color="green">384</FONT>            if (xData.length != yData.length) {<a name="line.384"></a>
<FONT color="green">385</FONT>                throw new IllegalArgumentException("Array lengths must be equal.");<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>            if (period &gt; xData.length) {<a name="line.388"></a>
<FONT color="green">389</FONT>                throw new IllegalArgumentException(<a name="line.389"></a>
<FONT color="green">390</FONT>                    "Period can't be longer than dataset."<a name="line.390"></a>
<FONT color="green">391</FONT>                );<a name="line.391"></a>
<FONT color="green">392</FONT>            }<a name="line.392"></a>
<FONT color="green">393</FONT>    <a name="line.393"></a>
<FONT color="green">394</FONT>            double[][] result = new double[xData.length - period][2];<a name="line.394"></a>
<FONT color="green">395</FONT>            for (int i = 0; i &lt; result.length; i++) {<a name="line.395"></a>
<FONT color="green">396</FONT>                result[i][0] = xData[i + period].doubleValue();<a name="line.396"></a>
<FONT color="green">397</FONT>                // holds the moving average sum<a name="line.397"></a>
<FONT color="green">398</FONT>                double sum = 0.0;<a name="line.398"></a>
<FONT color="green">399</FONT>                for (int j = 0; j &lt; period; j++) {<a name="line.399"></a>
<FONT color="green">400</FONT>                    sum += yData[i + j].doubleValue();<a name="line.400"></a>
<FONT color="green">401</FONT>                }<a name="line.401"></a>
<FONT color="green">402</FONT>                sum = sum / period;<a name="line.402"></a>
<FONT color="green">403</FONT>                result[i][1] = sum;<a name="line.403"></a>
<FONT color="green">404</FONT>            }<a name="line.404"></a>
<FONT color="green">405</FONT>            return result;<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>    <a name="line.408"></a>
<FONT color="green">409</FONT>    }<a name="line.409"></a>




























































</PRE>
</BODY>
</HTML>