The Histogram class constructs a histogram of data supplied using Tk widget classes. The XHistogram class also constructs a histogram, but then plots it using the 2D plotting system.
The most useful methods of both classes are summarized in below tables. The Histogram class counts the number of occurrences of data values that fall within each of a number of bins. Each bin represents a range of numbers. All bins have the same width, and the center of each bin will be an integer multiple of this width. Bin number 0 is always the one with the smallest center. Bins are added if new data arrives that does not fit within any of the existing bins. The getData method is used to read out the contents of a bin. If you start with bin number 0, and proceed until getData returns FALSE, you will have read all the bins.
Method 
Parameter 
Description 

Histogram (...) 

constructor 

double width = 1.0 
the width of each bin; bins are centered at integer multiples of this value 

int maxBins = 1000 
since bins are added as needed, it is wise to limit their number 
void add (...) 

add a new sample to the histogram 

double x 
a data point for the historgram 
int numCounts () 

return the number of data values used so far in the histogram 
double mean () 

return the average value of all observed data so far 
double variance () 

return the variance of the observed data so far 
getData (...) 

get the count for a given bin; return FALSE if the bin is out of range 

int binno 
starting at 0, the bin number 

int& count 
place to store the count for the given bin 

double& binCenter 
place to store the center of the given bin 
Method 
Parameter 
Description 

void initialize (...) 

start a new histogram 

Block* parent 
pointer to the block using the class 

double binWidth 
the width of each bin; bins are centered at integer multiples of this value 

const char* options 
options to pass to the 2D plotting system, in addition to bar nl brw 

const char* title 
title to put on the histogram 

const char* saveFile 
name of a file to save data to (or 0 if none) 

int maxBins = 1000 
limit the number of bins 
void addPoint (...) 

add a new sample to the histogram 

double y 
a data point for the histogram 
int numCounts () 

return the number of data values used so far in the histogram 
double mean () 

return the average value of all observed data so far 
double variance () 

return the variance of the observed data so far 
void terminate () 

plot the histogram using the 2D plotting system 