/* SPDX-License-Identifier: BSD-2-Clause */ /* * Copyright (C) 2019, Raspberry Pi Ltd * * histogram.cpp - histogram calculations */ #include <math.h> #include <stdio.h> #include "histogram.h" using namespace RPiController; uint64_t Histogram::cumulativeFreq(double bin) const { if (bin <= 0) return 0; else if (bin >= bins()) return total(); int b = (int)bin; return cumulative_[b] + (bin - b) * (cumulative_[b + 1] - cumulative_[b]); } double Histogram::quantile(double q, int first, int last) const { if (first == -1) first = 0; if (last == -1) last = cumulative_.size() - 2; assert(first <= last); uint64_t items = q * total(); while (first < last) /* binary search to find the right bin */ { int middle = (first + last) / 2; if (cumulative_[middle + 1] > items) last = middle; /* between first and middle */ else first = middle + 1; /* after middle */ } assert(items >= cumulative_[first] && items <= cumulative_[last + 1]); double frac = cumulative_[first + 1] == cumulative_[first] ? 0 : (double)(items - cumulative_[first]) / (cumulative_[first + 1] - cumulative_[first]); return first + frac; } double Histogram::interQuantileMean(double qLo, double qHi) const { assert(qHi > qLo); double pLo = quantile(qLo); double pHi = quantile(qHi, (int)pLo); double sumBinFreq = 0, cumulFreq = 0; for (double pNext = floor(pLo) + 1.0; pNext <= ceil(pHi); pLo = pNext, pNext += 1.0) { int bin = floor(pLo); double freq = (cumulative_[bin + 1] - cumulative_[bin]) * (std::min(pNext, pHi) - pLo); sumBinFreq += bin * freq; cumulFreq += freq; } /* add 0.5 to give an average for bin mid-points */ return sumBinFreq / cumulFreq + 0.5; }