---
myst:
    substitutions:
        bloc:
            python: 14-20,26-35
            cpp: 5-8,14-16,22-27
---
# Histogram

The histogram is present in {{root}} but it needs to be encapsulated when the user wants to choose 
an automatic method determining the number of **bins**. By default, the number of bins is given in 
the variable of the configuration file of {{root}} `.rootrc` of the directory `$ROOTSYS/etc`.
This information can be overloaded by an user file `.rootrc` in its *home directory ($HOME)*, or in 
a local file where {{root}} is executed. Several methods exist to determine the number of "bins" 
according to the characteristics of the variable to be visualised.

Again we consider the {{tds}} built from the `geyser.dat` file, to which we add the attribute *xnorm*, 
then the histograms will be plotted using the different methods of this new attribute.

{{                                                                                                  
    "```{literalinclude} " + parent_dir                                                             
    + "/roottest/uranie/doc/dataserver/vizualisation/" + language + "/draw_geyser_histograms." 
    + extension + "\n"
    + ":language: " + language + "\n"
    + ":lines: " + bloc[language] + "\n"                                                   
    + "```"                                                                                         
}}  

{{                                                                                                  
    "```{" "figure" "} " + parent_dir +                                                             
        "/roottest/build/uranie/doc/dataserver/vizualisation/" + language 
        + "/geyser_1/geyser_histograms.png\n"
    ":align: center\n"                                                                              
    ":name: dataserver_geyser_histograms\n"                                            
    + figure_scale + "\n"                                                                
    "\n"                                                                                            
    "Different histograms of the same attribute *xnorm* depending on the method for computing bins. 
    The values are respectively 100(root), 8 from sturges, 7 from fd and scoot.\n"                 
    "```"                                                                                           
}}