SimpleHistogramGenerator Class Reference

#include <SimpleHistogramGenerator.h>

Public Member Functions
int	binarySearch (const int &n, const std::vector< float > &array, const double &value) const
double	generate (RandomEngineAndDistribution const *) const
	The random generation. More...
	SimpleHistogramGenerator (TH1 *histo)
virtual	~SimpleHistogramGenerator ()
	Default destructor. More...

Private Attributes
double	binWidth
std::vector< float >	integral
	Integral. More...
int	nBins
	Pointer to the histogram. More...
double	nEntries
	Number of entries. More...
double	xMax
double	xMin

Detailed Description

Definition at line 21 of file SimpleHistogramGenerator.h.

Constructor & Destructor Documentation

SimpleHistogramGenerator()

SimpleHistogramGenerator::SimpleHistogramGenerator

(

TH1 *

histo

)

Constructor that perform the necessary integration and inversion steps xmin and xmax are the generation bounds, n is the internal table size and iter is the number of iterations for the numerical part.

Definition at line 8 of file SimpleHistogramGenerator.cc.

    :  //myHisto(histo),
      //theXaxis(histo->GetXaxis()),
      nBins(histo->GetXaxis()->GetNbins()),
      xMin(histo->GetXaxis()->GetXmin()),
      xMax(histo->GetXaxis()->GetXmax()),
      binWidth((xMax - xMin) / (float)nBins) {
  integral.reserve(nBins + 2);
  integral.push_back(0.);
  for (int i = 1; i <= nBins; ++i)
    integral.push_back(integral[i - 1] + histo->GetBinContent(i));
  integral.push_back(integral[nBins]);
  nEntries = integral[nBins + 1];
  for (int i = 1; i <= nBins; ++i)
    integral[i] /= nEntries;
}

References timingPdfMaker::histo, mps_fire::i, integral, nBins, and nEntries.

~SimpleHistogramGenerator()

virtual SimpleHistogramGenerator::~SimpleHistogramGenerator ( )

inlinevirtual

Default destructor.

Definition at line 29 of file SimpleHistogramGenerator.h.

{}

Member Function Documentation

binarySearch()

int SimpleHistogramGenerator::binarySearch	(	const int &	n,
		const std::vector< float > &	array,
		const double &	value
	)		const

Definition at line 37 of file SimpleHistogramGenerator.cc.

                                                                                                                 {
  // Binary search in an array of n values to locate value.
  //
  // Array is supposed  to be sorted prior to this call.
  // If match is found, function returns position of element.
  // If no match found, function gives nearest element smaller than value.
 
  int nabove, nbelow, middle;
  nabove = n + 1;
  nbelow = 0;
  while (nabove - nbelow > 1) {
    middle = (nabove + nbelow) / 2;
    if (value == array[middle - 1])
      return middle - 1;
    if (value < array[middle - 1])
      nabove = middle;
    else
      nbelow = middle;
  }
  return nbelow - 1;
}

References mps_check::array, and dqmiodumpmetadata::n.

Referenced by generate().

generate()

double SimpleHistogramGenerator::generate

(

RandomEngineAndDistribution const *

random

)

const

The random generation.

Definition at line 25 of file SimpleHistogramGenerator.cc.

                                                                                         {
  // return a random number distributed according the histogram bin contents.
  // NB Only valid for 1-d histograms, with fixed bin width.
 
  double r1 = random->flatShoot();
  int ibin = binarySearch(nBins, integral, r1);
  double x = xMin + (double)(ibin)*binWidth;
  if (r1 > integral[ibin])
    x += binWidth * (r1 - integral[ibin]) / (integral[ibin + 1] - integral[ibin]);
  return x;
}

References binarySearch(), binWidth, RandomEngineAndDistribution::flatShoot(), integral, nBins, diffTwoXMLs::r1, x, and xMin.

Referenced by PixelTemplateSmearerBase::smearHit(), and PixelTemplateSmearerBase::smearMergeGroup().

Member Data Documentation

binWidth

double SimpleHistogramGenerator::binWidth

private

Definition at line 50 of file SimpleHistogramGenerator.h.

Referenced by generate().

integral

std::vector<float> SimpleHistogramGenerator::integral

private

Integral.

Definition at line 53 of file SimpleHistogramGenerator.h.

Referenced by generate(), and SimpleHistogramGenerator().

nBins

int SimpleHistogramGenerator::nBins

private

Pointer to the histogram.

the axis Number of bins

Definition at line 44 of file SimpleHistogramGenerator.h.

Referenced by generate(), and SimpleHistogramGenerator().

nEntries

double SimpleHistogramGenerator::nEntries

private

Number of entries.

Definition at line 56 of file SimpleHistogramGenerator.h.

Referenced by SimpleHistogramGenerator().

xMax

double SimpleHistogramGenerator::xMax

private

Definition at line 47 of file SimpleHistogramGenerator.h.

xMin

double SimpleHistogramGenerator::xMin

private

Definition at line 47 of file SimpleHistogramGenerator.h.

Referenced by generate().