DONUT

Excel Usage

=DONUT(data, title, color_map, hole_size, legend)

• data (list[list], required): Input data (Labels, Values).
• title (str, optional, default: null): Chart title.
• color_map (str, optional, default: “viridis”): Color map for slices.
• hole_size (float, optional, default: 0.5): Size of the donut hole (0-1).
• legend (str, optional, default: “true”): Show legend.

Returns (object): Matplotlib Figure object (standard Python) or base64 encoded PNG string (Pyodide).

Examples

Example 1: Simple donut chart with 3 categories

Inputs:

data
A	30
B	50
C	20

Excel formula:

=DONUT({"A",30;"B",50;"C",20})

Expected output:

"chart"

Example 2: Donut chart with title and legend

Inputs:

data		title	legend
Q1	100	Quarterly Sales	true
Q2	150
Q3	120
Q4	180

Excel formula:

=DONUT({"Q1",100;"Q2",150;"Q3",120;"Q4",180}, "Quarterly Sales", "true")

Expected output:

"chart"

Example 3: Donut with plasma colormap and small hole

Inputs:

data		color_map	hole_size
Category A	25	plasma	0.3
Category B	35
Category C	40

Excel formula:

=DONUT({"Category A",25;"Category B",35;"Category C",40}, "plasma", 0.3)

Expected output:

"chart"

Example 4: Donut with large center hole

Inputs:

data		hole_size
Item 1	60	0.7
Item 2	40

Excel formula:

=DONUT({"Item 1",60;"Item 2",40}, 0.7)

Expected output:

"chart"

Python Code

import sys
import matplotlib
IS_PYODIDE = sys.platform == "emscripten"
if IS_PYODIDE:
    matplotlib.use('Agg')
import matplotlib.pyplot as plt
import io
import base64
import numpy as np

def donut(data, title=None, color_map='viridis', hole_size=0.5, legend='true'):
    """
    Create a donut chart from data.

    See: https://matplotlib.org/stable/gallery/pie_and_polar_charts/pie_and_donut_labels.html

    This example function is provided as-is without any representation of accuracy.

    Args:
        data (list[list]): Input data (Labels, Values).
        title (str, optional): Chart title. Default is None.
        color_map (str, optional): Color map for slices. Valid options: Viridis, Plasma, Inferno, Magma, Cividis. Default is 'viridis'.
        hole_size (float, optional): Size of the donut hole (0-1). Default is 0.5.
        legend (str, optional): Show legend. Valid options: True, False. Default is 'true'.

    Returns:
        object: Matplotlib Figure object (standard Python) or base64 encoded PNG string (Pyodide).
    """
    def to2d(x):
        return [[x]] if not isinstance(x, list) else x

    try:
        data = to2d(data)

        if not isinstance(data, list) or len(data) < 1:
            return "Error: Data must be a non-empty list"

        # Extract labels and values
        labels = []
        values = []
        for row in data:
            if not isinstance(row, list) or len(row) < 2:
                continue
            try:
                labels.append(str(row[0]))
                values.append(float(row[1]))
            except (ValueError, TypeError):
                continue

        if len(labels) == 0 or len(values) == 0:
            return "Error: No valid data rows found"

        if any(v < 0 for v in values):
            return "Error: Values must be non-negative"

        # Create figure
        fig, ax = plt.subplots(figsize=(8, 6))

        # Create donut chart
        wedges, texts, autotexts = ax.pie(
            values,
            labels=labels,
            autopct='%1.1f%%',
            startangle=90,
            wedgeprops=dict(width=1-hole_size),
            colors=plt.cm.get_cmap(color_map)(np.linspace(0, 1, len(values)))
        )

        # Set title
        if title:
            ax.set_title(title)

        # Handle legend
        if legend == "true":
            ax.legend(labels, loc="best")

        # Equal aspect ratio ensures circular shape
        ax.axis('equal')

        if IS_PYODIDE:
            buf = io.BytesIO()
            plt.savefig(buf, format='png', bbox_inches='tight')
            plt.close(fig)
            buf.seek(0)
            img_base64 = base64.b64encode(buf.read()).decode('utf-8')
            return f"data:image/png;base64,{img_base64}"
        else:
            return fig
    except Exception as e:
        return f"Error: {str(e)}"

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