BULLET

Excel Usage

=BULLET(data, title, target, color_ranges, color_measure, legend)

• data (list[list], required): Input data (Labels, Measured).
• title (str, optional, default: null): Chart title.
• target (float, optional, default: 0): Target value.
• color_ranges (str, optional, default: null): Zone colors (comma-separated).
• color_measure (str, optional, default: “black”): Measured bar color.
• legend (str, optional, default: “false”): Show legend.

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

Examples

Example 1: Basic bullet chart with target

Inputs:

data		target
Sales	80	100
Revenue	120

Excel formula:

=BULLET({"Sales",80;"Revenue",120}, 100)

Expected output:

"chart"

Example 2: Bullet chart with title

Inputs:

data		target	title
Q1	90	100	Quarterly Performance
Q2	110

Excel formula:

=BULLET({"Q1",90;"Q2",110}, 100, "Quarterly Performance")

Expected output:

"chart"

Example 3: Bullet chart with colored zones

Inputs:

data		target	color_ranges
Metric A	75	100	lightgray,yellow,lightgreen

Excel formula:

=BULLET({"Metric A",75}, 100, "lightgray,yellow,lightgreen")

Expected output:

"chart"

Example 4: Bullet chart with legend

Inputs:

data		target	legend
Score	85	90	true

Excel formula:

=BULLET({"Score",85}, 90, "true")

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 bullet(data, title=None, target=0, color_ranges=None, color_measure='black', legend='false'):
    """
    Create a bullet chart for visual comparison against a target.

    See: https://matplotlib.org/stable/gallery/lines_bars_and_markers/barh.html

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

    Args:
        data (list[list]): Input data (Labels, Measured).
        title (str, optional): Chart title. Default is None.
        target (float, optional): Target value. Default is 0.
        color_ranges (str, optional): Zone colors (comma-separated). Default is None.
        color_measure (str, optional): Measured bar color. Default is 'black'.
        legend (str, optional): Show legend. Valid options: True, False. Default is 'false'.

    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) == 0:
            return "Error: Data must be a non-empty 2D list"

        # Extract labels and measured values
        labels = []
        measured = []

        for row in data:
            if not isinstance(row, list) or len(row) < 2:
                continue

            try:
                label = str(row[0]) if row[0] else "Item"
                value = float(row[1])

                labels.append(label)
                measured.append(value)
            except (TypeError, ValueError):
                continue

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

        # Create the figure
        fig, ax = plt.subplots(figsize=(10, max(3, len(labels) * 0.8)))

        y_pos = np.arange(len(labels))

        # Determine the maximum value for scaling
        max_value = max(max(measured), target if target > 0 else 0)

        # Parse color ranges for background zones
        if color_ranges:
            colors = [c.strip() for c in str(color_ranges).split(',')]
            # Draw background zones
            zone_width = max_value / len(colors)
            for i, color in enumerate(colors):
                ax.barh(y_pos, zone_width, left=i * zone_width, 
                       color=color, alpha=0.3, height=0.8)

        # Draw measured bars
        ax.barh(y_pos, measured, height=0.4, color=color_measure, 
               edgecolor='black', linewidth=1, label='Measured' if legend == "true" else None)

        # Draw target line if specified
        if target > 0:
            for i in y_pos:
                ax.plot([target, target], [i - 0.4, i + 0.4], 
                       color='red', linewidth=2, label='Target' if i == 0 and legend == "true" else None)

        ax.set_yticks(y_pos)
        ax.set_yticklabels(labels)
        ax.invert_yaxis()
        ax.set_xlabel('Value')

        if title:
            ax.set_title(str(title))

        if legend == "true":
            handles, labels_legend = ax.get_legend_handles_labels()
            # Remove duplicate labels
            by_label = dict(zip(labels_legend, handles))
            ax.legend(by_label.values(), by_label.keys(), loc='best')

        ax.grid(True, axis='x', alpha=0.3)
        plt.tight_layout()

        if IS_PYODIDE:
            buf = io.BytesIO()
            plt.savefig(buf, format='png', dpi=100, bbox_inches='tight')
            buf.seek(0)
            img_base64 = base64.b64encode(buf.read()).decode('utf-8')
            plt.close(fig)
            return f"data:image/png;base64,{img_base64}"
        else:
            return fig
    except Exception as e:
        return f"Error: {str(e)}"

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