Plotting Grouped Bar Plots

A grouped bar plot or histogram is made up of rectangular bars, whose length is proportional to the values they represent. If a target is defined, bars with a different color for each value of the target are plotted.

It contains the following attributes:





Ether x or y must be specified


Either x or y must be specified

It cannot be a nominal value








Fitting curve

If Normal Distribution is selected, the Gaussian curve that best fits the data distribution is drawn.

Continuous attributes only.

Show null values

If selected, missing values are displayed.

Reverse order

If selected, the order of values in the x axis is reversed.

By default the order is a-z; if selected the order becomes z-a.

Nominal attributes only.

Sort by value

If selected bars are sorted according to their height (i.e. the y value).

Nominal attributes only.


Displays the bars vertically or horizontally.

Displayed value

Select which value should be plotted from the following possibilities:

  • Standard: the total (if a y is present, the aggregate operator of the y as defined by another option as explained below; if y is not present the count);

  • Total percentage: the percentage of the bar on the total. The total is computed according to the criteria explained in the previous point.

  • Target percentage: the percentage of the bar on the target.

For example, if x has three values: ab and c and the average (or sum, mode etc., according to the selected aggregation operator) of y is 5 for a,10 for b and 20 for c. If Standard is selected as the Displayed Value the height of the three bars is 5, 10 and 20. If Total Percentage is selected the percentage is displayed. As the sum is 35, the three bars will have the following heights: 100*5/(35), 100*10/(35), 100*20/(35).

X attribute

Number of bins

Defines the number of displayed intervals for the x attribute.

Target attribute

Number of bins

Defines the number of displayed intervals for the target attribute.

Y attribute

Aggregate operator

The operator required to aggregate data. This is used to determine the height of the bars according to the option selected in Displayed value.

Possible values are average, maximum, median, minimum, mode and sum.


The following examples are based on the Adult dataset.

Scenario data can be found in the Datasets folder in your Rulex installation.




Basic grouped bar plot

Setting the attribute age attribute in the x cell will display a 10-bin histogram based on age.

In this case, the height of each bar corresponds to the number of occurrences for each value.

Grouped bar plot with weight

Adding the capital-gain attribute to the y cell will display the age histogram, weight-based on capital-gain values.

The height of each bar is is the average of the capital-gain (or the sum, maximum etc. according to the specified Aggregate operator).

Grouped bar plot with target

Adding the relationship attribute to the Target cell will display the distribution of relationship classes in the previous histogram, in different colors.