Bar Charts

A bar chart is a visual graph that uses rectangular bars to compare the size of different categories. The BarChart module allows you to generate visualizations from dictionaries mapping strings to numerical values.

Create a simple Bar Chart

Let's first prepare the data and label formatting before initializing a simple chart using it.

# Define the chart title
chart_title = "Coffee Grinder Prices"

# Define the chart data
coffee_grinder_prices = {
    "Manual": 29,
    "Blade": 45,
    "Burr":  120,
}

# Custom formatters can override default label values
def custom_label_formatter(_category: str, value: int) -> str:
    return f"{value} $"

# Create the chart object
chart = BarChart(
    coffee_grinder_prices,
    title=chart_title,
    inside_label_formatter=custom_label_formatter,
)

There are a number of configuration parameters available to fine-tune the layout and appearance of the BarChart, which can be passed as keyword arguments.

Parameter	Effect	Default
position	Top-left chart origin as (x, y)	(0, 0)
show_axis	Toggles axis and tick display	False
bar_width	Width of each bar	40
bar_spacing	Horizontal spacing between bars	20
max_bar_height	Height of the tallest bar	200
bar_colors	Single color or list of colors applied to bars	"#66ccff"
bar_fill_color	Overrides fill color for all bars	None
bar_stroke_color	Stroke color for bar outlines	"#000000"
title	Optional chart title	None
title_text_format	Text formatting for the title	TextFormat()
base_text_format	Formatting for labels below bars	TextFormat()
inside_text_format	Formatting for labels rendered inside bars	TextFormat()
background_color	Optional background rectangle behind the chart	None
axis_tick_count	Number of tick intervals on the chart axis	5
axis_text_format	Formatting for axis tick labels	TextFormat()
base_label_formatter	Callable that formats the category label below each bar	lambda l,v: l
inside_label_formatter	Callable that formats values printed inside each bar	lambda l,v: str(v)
bar_object	Optional template Object used to generate each bar	None

Note: When you provide a bar template object, every bar in the chart will inherit its styling (such as rounded corners, glass or shadow). However, properties like the bar’s value, color and size are always controlled by the BarChart itself and will override the template’s values.

With a few visual adjustments, the resulting chart renders as: