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76 lines
2.1 KiB
76 lines
2.1 KiB
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef _CENTRAL_TENDENCY_STATISTICS_H
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#define _CENTRAL_TENDENCY_STATISTICS_H
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#include <math.h>
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// Not multithread safe
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class CentralTendencyStatistics {
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public:
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CentralTendencyStatistics() :
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mMean(NAN), mMedian(NAN), mMinimum(INFINITY), mMaximum(-INFINITY), mN(0), mM2(0),
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mVariance(NAN), mVarianceKnownForN(0), mStddev(NAN), mStddevKnownForN(0) { }
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~CentralTendencyStatistics() { }
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// add x to the set of samples
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void sample(double x);
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// return the arithmetic mean of all samples so far
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double mean() const { return mMean; }
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// return the minimum of all samples so far
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double minimum() const { return mMinimum; }
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// return the maximum of all samples so far
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double maximum() const { return mMaximum; }
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// return the variance of all samples so far
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double variance() const;
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// return the standard deviation of all samples so far
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double stddev() const;
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// return the number of samples added so far
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unsigned n() const { return mN; }
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// reset the set of samples to be empty
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void reset();
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private:
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double mMean;
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double mMedian;
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double mMinimum;
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double mMaximum;
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unsigned mN; // number of samples so far
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double mM2;
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// cached variance, and n at time of caching
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mutable double mVariance;
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mutable unsigned mVarianceKnownForN;
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// cached standard deviation, and n at time of caching
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mutable double mStddev;
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mutable unsigned mStddevKnownForN;
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};
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#endif // _CENTRAL_TENDENCY_STATISTICS_H
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