FUNNEL

Excel Usage

=FUNNEL(data, title, color_map, values, 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 stages.
• values (str, optional, default: “true”): Show numeric values.
• legend (str, optional, default: “false”): Show legend.

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

Examples

Example 1: Simple funnel chart with 4 stages

Inputs:

data
Awareness	1000
Interest	600
Consideration	300
Purchase	100

Excel formula:

=FUNNEL({"Awareness",1000;"Interest",600;"Consideration",300;"Purchase",100})

Expected output:

"chart"

Example 2: Funnel chart with title and values

Inputs:

data		title	values
Stage 1	500	Sales Funnel	true
Stage 2	400
Stage 3	200

Excel formula:

=FUNNEL({"Stage 1",500;"Stage 2",400;"Stage 3",200}, "Sales Funnel", "true")

Expected output:

"chart"

Example 3: Funnel with plasma colormap

Inputs:

data		color_map
Top	800	plasma
Middle	500
Bottom	200

Excel formula:

=FUNNEL({"Top",800;"Middle",500;"Bottom",200}, "plasma")

Expected output:

"chart"

Example 4: Funnel chart with legend

Inputs:

data		legend	values
Lead	1200	true	true
Qualified	800
Closed	300

Excel formula:

=FUNNEL({"Lead",1200;"Qualified",800;"Closed",300}, "true", "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 funnel(data, title=None, color_map='viridis', values='true', legend='false'):
    """
    Create a funnel chart for stages in a process.

    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, Values).
        title (str, optional): Chart title. Default is None.
        color_map (str, optional): Color map for stages. Valid options: Viridis, Plasma, Inferno, Magma, Cividis. Default is 'viridis'.
        values (str, optional): Show numeric values. Valid options: True, False. Default is 'true'.
        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) < 1:
            return "Error: Data must be a non-empty list"

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

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

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

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

        # Create funnel using horizontal bars centered
        y_pos = np.arange(len(labels))
        colors_list = plt.cm.get_cmap(color_map)(np.linspace(0, 1, len(vals)))

        # Center the bars
        max_val = max(vals) if vals else 1
        left_edges = [(max_val - v) / 2 for v in vals]

        bars = ax.barh(y_pos, vals, left=left_edges, color=colors_list, edgecolor='black')

        # Add value labels if requested
        if values == "true":
            for i, (bar, val) in enumerate(zip(bars, vals)):
                ax.text(max_val / 2, i, f'{val}', ha='center', va='center', fontweight='bold')

        # Set labels
        ax.set_yticks(y_pos)
        ax.set_yticklabels(labels)
        ax.invert_yaxis()  # Top to bottom

        if title:
            ax.set_title(title)

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

        # Remove x-axis for cleaner look
        ax.set_xticks([])
        ax.spines['top'].set_visible(False)
        ax.spines['right'].set_visible(False)
        ax.spines['bottom'].set_visible(False)

        plt.tight_layout()

        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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