How to Add Group Labels to Bar Charts with Python?

Adding Group Labels to Bar Charts with Python

In data visualization, it can be useful to add group labels to bar charts in order to categorize and clarify the displayed data. While Matplotlib does not have a built-in function for this, a custom solution can be implemented using the following code:

def mk_groups(data):
    ...

def add_line(ax, xpos, ypos):
    ...

def label_group_bar(ax, data):
    ...

The mk_groups function converts the input dictionary into a specific data format suitable for creating the bar chart. This format consists of a list of lists, where each inner list represents a group and contains tuples of (label, number of bars). The add_line function draws vertical lines in the subplot to separate the groups. The label_group_bar function takes the dictionary and uses the data format generated by mk_groups to create the bar chart with the group labels located beneath the corresponding bars.

To use this solution, provide the data in a dictionary structure, where the top-level keys are the group labels and the subsequent levels contain the labels and values for the bars within each group. The label_group_bar function will then create a bar chart with the desired group labels.

Example:

Consider the following data:

data = {'Room A':
           {'Shelf 1':
               {'Milk': 10,
                'Water': 20},
            'Shelf 2':
               {'Sugar': 5,
                'Honey': 6}
           },
        'Room B':
           {'Shelf 1':
               {'Wheat': 4,
                'Corn': 7},
            'Shelf 2':
               {'Chicken': 2,
                'Cow': 1}
           }
       }

Calling label_group_bar(ax, data) will create a bar chart with the groups "Room A" and "Room B" and their associated labels. The resulting chart will resemble the one below:

[Image of bar chart with group labels]

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