prf_utils::His2D Class Reference

A histogram with 2 independent variables. More...

#include <His2D.hh>

Public Member Functions
His2D &	operator= (const His2D &)
	One can assign a histogram to another.
void	init ()
	Necessary to call this after specifying number of bins etc.
void	reset ()
	Does not deallocate memory, but clears the collected statistics.
void	Range (double x0, double x1, double x2, double x3)
	Set range in x and y directions.
void	XRange (double x0, double x1)
	Set only the x range.
void	YRange (double x0, double x1)
	Set only the y range.
void	NXbins (int v)
	Set the number of bins in the X-axis.
void	NYbins (int v)
	Set the number of bins in the Y-axis.
int	NXbins () const
	Return the current number of bins in the X-axis.
int	NYbins () const
	Return the current number of bins in the Y-axis.
double	Xmin () const
	Return the lower limit of the current X-range.
double	Xmax () const
	Return the upper limit of the current X-range.
double	Ymin () const
	Return the lower limit of the current Y-range.
double	Ymax () const
	Return the upper limit of the current Y-range.
double	xval (int i)
	X value for the i'th bin on the X-axis.
double	yval (int i)
	Y value for the i'th bin on the Y-axis.
double	val (int i, int j)
	Z value for the i'th bin along X and j'th bin along Y-axis.
int	put (double x, double y)
	Put a new datapoint (x,y) into the histogram.
double	normalize ()
	Convert the collected frequency data to probabilities.
void	Export (const char *filename, int fmt=3)
	Save histogram information in a file for plotting.
int	Import (const char *filename)
	Read back histogram information from exported text files.
void	save_state (const char *filename)
	Save current state of sampling in a binary file to resume counting later.
void	read_state (const char *filename)
	Retrieve stored sampling state to resume counting.
His2D &	operator+= (const His2D &)
	Add the contents of another histogram.
void	Projection_X (std::vector< double > &hsx)
	For each x, return Sum z(x,y) | y=0..ymax.
void	Projection_Y (std::vector< double > &hsy)
	For each y, return Sum z(x,y) | x=0..xmax.

Detailed Description

His2D represents histograms of the type dP/dxdy to chart out the probability distribution of a variable z as a function of two variables x and y.

Data can be stored in two supported layouts in text files. To describe we use the notation zij=P(xi,yj).

The layout means, when the histogram data is written to a file, it is formatted like this:

x0 y0 z00
x0 y1 z01
x0 y2 z02
...
x0 yn z0n

x1 y0 z10
x1 y1 z11
...

In the second supported data layout, the data is saved in 3 files. One representing just the x values, { x0, x1,... }, one with only the y values {y1,y2 ...}, and one with the z values :

z00 z01 z02 ... z0n
z10 z11 z12 ... z1n
z20 ...
...
where n is (n_ybins -1) This format takes less space on disk. It became the default layout in PROFASI v 1.4.

Member Function Documentation

int His2D::Import

(

const char *

filename

)

Import is only implemented for files exported with the default format, fmt=3. In this format, there are a few comment lines beginning with "#" giving ranges and number of bins. Then there is a matrix M of data of (nxbins+1) rows and (nybins+1) columns. The top-left element, with index (0,0) is always 0. The elements M[0,1+j], for j in the range (0,nybins) are the centres of the ybins for the data. Similarly, M[1+i,0] for i in range (0,nxbins) are the centres of xbins. The elements M[1+i,1+j] with i in range (0,nxbins) and j in range (0,nybins) then represent the probabilities P(X[i],Y[j]).

double His2D::normalize

(

)

After a call to normalize, the sum of all elements in the histogram is 1, provided all attempted put(x,y) operations succeeded, i.e., there were no out of range values.

int His2D::put	(	double	x,
		double	y
	)

We are concerned with keeping track of how often an certain combination (x,y) occurs. This function should be called for every sampling event. Then after a large number of sampling events, the histogram will contain the probabilities (frequencies, if not normalized) for the different (x,y) pairs.

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The documentation for this class was generated from the following files:

• model/Aux/His2D.hh
• model/Aux/His2D.cc