CNHistogram -- Reduction of statistical data to an histogram.

SYNOPSIS

#include <CNCL/Histogram.h>

TYPE

CN_HISTOGRAM

BASE CLASSES

CNStatistics

DERIVED CLASSES

None

RELATED CLASSES

None

DESCRIPTION

CNHistogram contains functions to reduce input data to a histogram. It provides two main output formats: Either you can create an easy readable array or you can write the results of the evaluation to a file in a format that can further be processed by 'gnuplot'.

Constructors

CNHistogram();

Not yet implemented

CNHistogram(CNParam *);

Not yet implemented

CNHistogram(char *aName, double l_border, double u_border,

short int num, double normalization = 0.0,

char* aDescription = NIL);

Initializes CNHistogram.

The arguments are:

aName: Name of the histogram

l_border: Lower border for evaluation

u_border: Upper border for evaluation

num: Number of bins

normalization: The total number of entries in the histogram is normalized to this value. The default value '0' means, that no normalization is performed.

In addition to the member functions required by CNCL, CNHistogram provides:

void put( double );

Input function of the histogram. The input value is sampled into the histogram.

double mean() const;

Returns the mean value of the input sequence.

double variance() const;

Returns the variance of the input sequence.

long trials() const;

Returns the number of values sampled in the histogram.

double min() const;

Returns the minimum input value.

double max() const;

Returns the maximum input value.

boolean end() const;

Always returns FALSE as an histogram evaluation never reaches an end.

void reset();

Not yet implemented, but required by base class CNStatistics. (Might be implemented later if necessary).

Phase status() const;

Returns the state of evaluation. Since evaluation never reaches an end, status only returns INITIALIZE (no value in histogram) or ITERATE.

void set_norm(double);

Sets normalization to new value. Does not change any internal data. Only the representation of the output is changed. It is therefore possible to change normalization several times during evaluation of a histogram.

void print_header (ostream &, char * = "") const;

Writes header of histogram including statistic informations into the specified output stream. All lines are prefixed with the string given in the (optional) second parameter.

void print_histo(ostream &) const;

Writes the histogram data into the specified output stream in a human readable format.

void print_file(char*);

Creates output file and uses print_header and print_histo to fill it.

void plot_histo(ostream &, int = 0);

Writes the histogram data and the header into the specified output stream to be used as input values for gnuplot to draw the histogram. The header is written with print_header prefixed with the string "# " and therefore ignored by gnuplot. The (optional) second parameter specifies the drawing style: default 0 means that all vertical lines are drawn to the value of the next step (Step-histogram) a value != 0 means that all vertical lines are drawn down to the x-axis (Box-histogram). Those output lines, that differ in both drawing styles are either beginning with `# ' (Step-style) or with a blank ` '(Box-style). Thus the drawing style can easily be converted with a text editor by changing those lines appropriately. As only points are written, the plot command in `gnuplot' has to given with the specification with lines.

void plot_file(char*, int);

Creates output file and uses plot_histo to fill it. The second parameter specifies the drawing style used by plot_histo.

In addition the following operators are defined:

ostream &operator << (ostream &strm, const CNHistogram &obj);

Defines operator << to provide output of CNHistogram-objects to ostream. The member functions print_header and print_histo are called for 'obj'.

ostream &operator << (ostream &strm, const CNHistogram *obj);

Same functionality as above.

Also defined is a static member functions, that can very easily be used to sample data from a file into a histogram

static CNHistogram * CNHistogram::fill_histo_from_file(char * infile, double lower_bound, double upper_bound, short int number_of_bins, double normalisation, short int use_data_column);

Data is read from file 'infile' and values from column 'use_data_column' are sampled into the histogram newly created and returned by the function. The other parameters correspond to those described above. This function is used e.g. by the test program tHistogram.

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