BoxPlot.pg

#


@data = urand(100, 25, 75, 6);

$boxplotA = StatPlot(
    xmin            =>  0,
    xmax            => 200,
    xtick_delta     =>  25,
    show_grid       =>  0,
    ymin            => -5,
    ymax            =>  25,
    yvisible        =>  0,
    aspect_ratio    =>  4,
    rounded_corners => 1
);

$boxplotA->add_boxplot(~~@data, fill_color => 'lightblue', stroke_width => 1);

# the five point summary is needed for the alt text:

@five_point = five_point_summary(@data);
$minA       = Round($five_point[0]);
$q1A        = Round($five_point[1]);
$medA       = Round($five_point[2]);
$q3A        = Round($five_point[3]);
$maxA       = Round($five_point[4]);

$alt_textA =
    "A horizontal box plot with the box between $q1A and $q3A and vertical "
    . "line at $medA. The is line from the box to the left from $q1A to $minA and a "
    . "line to the right from $q3A to $maxA.";

# Alternatively, we can set these value for the plot.

$boxplotB = StatPlot(
    xmin            => 100,
    xmax            => 400,
    ymin            => -5,
    ymax            =>  25,
    xtick_delta     =>  50,
    yvisible        =>  0,
    show_grid       =>  0,
    aspect_ratio    =>  4,
    rounded_corners => 1
);

$minB = random(150, 175, 5);
$q1B  = random(180, 225, 5);
$medB = random(250, 275, 5);
$q3B  = random(280, 320, 10);
$maxB = random(325, 350, 5);

$boxplotB->add_boxplot({
    min      => $minB,
    q1       => $q1B,
    median   => $medB,
    q3       => $q3B,
    max      => $maxB,
    outliers => [ 115, 130, 375 ]
});

$alt_textB =
    "A horizontal box plot with the box between $q1B and $q3B and vertical "
    . "line at $medA. The is line from the box to the left from $q1B to $minB and a "
    . "line to the right from $q3B to $maxB.  There are also 3 small plus signs at "
    . "115, 130 and 375.";

Setup

The urand function is used for normally distributed random numbers. This example generates an array of length 75 with mean 100 and standard deviation 25. To create a graph, start with a StatPlot. The min and max options in the two directions give the bounding box of the plot. The tick_delta for each direction gives the distance between tick marks and the minor option is the number of minor ticks between each tick.

The box plot is created with the add_boxplot method in which the data is the first argument (it is an array reference, which is why the ~~ is needed). The remaining arguments are options to the box plot. See StatisticalPlots.pl for other options to this method.

The second box plot shows that the min/max, median and quartiles can be passed in as an alternative to an array reference of numbers. Make sure that an alternate text is added to all graphs for accessibility. Be detailed.

Boxplot

Complete Code

POD for Macro Files

PG problem file

Explanation