Apache Common Math Stat

最新推荐文章于 2024-06-16 13:22:42 发布

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最新推荐文章于 2024-06-16 13:22:42 发布

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本文介绍了Apache Commons Math库中的统计组件DescriptiveStatistics与SummaryStatistics的区别与应用。DescriptiveStatistics缓存输入数据以便计算滚动统计量，而SummaryStatistics不缓存数据，适用于能够通过一次遍历计算得出的统计量。此外还提到了多变量统计和同步统计组件的使用场景。

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http://commons.apache.org/proper/commons-math/userguide/stat.html

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DescriptiveStatistics maintains the input data in memory and has the capability of producing "rolling" statistics computed from a "window" consisting of the most recently added values.

SummaryStatistics does not store the input data values in memory, so the statistics included in this aggregate are limited to those that can be computed in one pass through the data without access to the full array of values.

如果不需要cache，one pass就可以算出来，用SummaryStatistics

DescriptiveStatistics 会cache所有数据在memory，用于无法one pass算出来的，支持window和rolling

SummaryStatistics can be aggregated using AggregateSummaryStatistics. This class can be used to concurrently gather statistics for multiple datasets as well as for a combined sample including all of the data.

MultivariateSummaryStatistics is similar to SummaryStatistics but handles n-tuple values instead of scalar values. It can also compute the full covariance matrix for the input data.

Neither DescriptiveStatistics nor SummaryStatistics is thread-safe. SynchronizedDescriptiveStatistics and SynchronizedSummaryStatistics, respectively, provide thread-safe versions for applications that require concurrent access to statistical aggregates by multiple threads.SynchronizedMultivariateSummaryStatistics provides thread-safe MultivariateSummaryStatistics.

There is also a utility class, StatUtils, that provides static methods for computing statistics directly from double[] arrays.

一些变体，

有StatUtils可以方便的使用，

例子，看原文，很好懂