67 lines
1.5 KiB
Java
67 lines
1.5 KiB
Java
package patternmatching;
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import java.io.FileNotFoundException;
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import java.util.Arrays;
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import java.util.stream.Collectors;
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public final class Statistics {
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private final long[] data;
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private Double mean = null;
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private Double variance = null;
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private Statistics(long[] data) {
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this.data = data;
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}
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double getMean() {
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if (mean == null) {
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mean = (double) Arrays.stream(data).sum() / data.length;
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}
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return mean;
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}
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double getVariance() {
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if (variance == null) {
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final double mean = getMean();
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double temp = 0;
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for(double a : data) {
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temp += (a-mean)*(a-mean);
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}
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variance = temp/(data.length-1);
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}
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return variance;
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}
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double getStddev() {
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return Math.sqrt(getVariance());
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}
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double getMedian() {
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Arrays.sort(data);
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if (data.length % 2 == 0) return (data[(data.length / 2) - 1] + data[data.length / 2]) / 2.0;
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return data[data.length / 2];
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}
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static Statistics from(long[] data) {
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return new Statistics(data);
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}
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@Override
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public String toString() {
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return String.format(
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"mean=%.2fms stddev=%.2fms median=%.2fms",
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getMean()/1000,
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getStddev()/1000,
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getMedian()/1000
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);
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}
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public String asCSv() {
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final String csv = Arrays.stream(data).mapToObj(String::valueOf).collect(Collectors.joining(","));
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return csv;
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}
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}
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