98 lines
2.3 KiB
C++
98 lines
2.3 KiB
C++
/*
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* ContinuousSample.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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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 CONTINUOUSSAMPLE_H
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#define CONTINUOUSSAMPLE_H
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#pragma once
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#include "flow/Platform.h"
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#include "flow/IRandom.h"
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#include <vector>
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#include <algorithm>
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#include <cmath>
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template <class T>
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class ContinuousSample {
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public:
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explicit ContinuousSample( int sampleSize ) : sampleSize( sampleSize ), populationSize( 0 ), sorted( true ), _min(T()), _max(T()) {}
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ContinuousSample<T>& addSample(T sample) {
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if( !populationSize )
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_min = _max = sample;
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populationSize++;
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sorted = false;
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if( populationSize <= sampleSize ) {
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samples.push_back( sample );
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} else if( g_random->random01() < ( (double)sampleSize / populationSize ) ) {
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samples[ g_random->randomInt( 0, sampleSize ) ] = sample;
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}
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_max = std::max( _max, sample );
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_min = std::min( _min, sample );
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return *this;
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}
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double mean() {
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if (!samples.size()) return 0;
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T sum = 0;
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for( int c = 0; c < samples.size(); c++ )
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sum += samples[ c ];
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return (double)sum / samples.size();
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}
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T median() {
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return percentile( 0.5 );
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}
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T percentile( double percentile ) {
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if( !samples.size() || percentile < 0.0 || percentile > 1.0 )
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return T();
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sort();
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int idx = std::floor( ( samples.size() - 1 ) * percentile );
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return samples[ idx ];
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}
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T min() { return _min; }
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T max() { return _max; }
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void clear() {
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samples.clear();
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populationSize = 0;
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sorted = true;
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_min = _max = 0; // Doesn't work for all T
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}
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private:
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int sampleSize;
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uint64_t populationSize;
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bool sorted;
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std::vector<T> samples;
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T _min, _max;
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void sort() {
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if( !sorted && samples.size() > 1 )
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std::sort( samples.begin(), samples.end() );
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sorted = true;
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}
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};
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#endif
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