Explicitly Set Level in Multi-Level Sankey using Plotly: A Step-by-Step Guide

Are you tired of dealing with messy and unclear Sankey diagrams? Do you want to take your data visualization game to the next level (pun intended)? Look no further! In this article, we’ll dive into the world of multi-level Sankey diagrams using Plotly and explore how to explicitly set levels to create stunning and informative visualizations.

What is a Sankey Diagram?

A Sankey diagram is a type of flow-based visualization that’s used to depict the magnitude of flow between nodes in a process. It’s commonly used in energy, material, and cost flow analysis. Sankey diagrams consist of nodes (representing the process steps) and edges (representing the flows between nodes). The width of the edges is proportional to the magnitude of the flow.

Multi-Level Sankey Diagrams: The Next Level

Multi-level Sankey diagrams take the classic Sankey to the next level (again, pun intended) by allowing for multiple levels of nodes. This enables us to visualize more complex processes and relationships between nodes. However, with great power comes great complexity. Explicitly setting levels in multi-level Sankey diagrams can be a challenge, but fear not, dear reader, for we’re about to tackle this challenge head-on!

Why Explicitly Set Levels?

Explicitly setting levels in multi-level Sankey diagrams is crucial for creating clear and informative visualizations. By doing so, you can:

• Clearly distinguish between different levels of nodes
• Highlight the relationships between nodes across different levels
• Create a more organized and structured visualization
• Improve the overall aesthetic appeal of your Sankey diagram

Preparing Your Data

Before we dive into the world of Plotly, let’s prepare our data. For this example, we’ll use a simple dataset representing energy flows between different stages of a power plant.

In this dataset, we have four columns: Source, Target, Value, and Level. The Level column is where we’ll explicitly set the level for each node.

Creating the Multi-Level Sankey Diagram

import plotly.graph_objects as go

fig = go.Figure(data=[go.Sankey(
    node=dict(
      pad=15,
      thickness=20,
      line=dict(color="black", width=0.5),
      label=["Fuel", "Boiler", "Turbine", "Generator", "Transformer"],
      color=["blue", "orange", "green", "red", "yellow"],
      level=[0, 1, 2, 3, 3]  # Explicitly set levels
    ),
    link=dict(
      source=[0, 1, 2, 3],  # indices correspond to labels
      target=[1, 2, 3, 4],
      value=[100, 80, 60, 50]
    )
)])

fig.update_layout(title_text="Multi-Level Sankey Diagram", font_size=10)

fig.show()

node=dict(
  ...
  color=["blue" if level == 0 else "orange" if level == 1 else "green" if level == 2 else "red" if level == 3 else "yellow" for level in [0, 1, 2, 3, 3]]
  ...
)

link=dict(
  ...
  color=["gray" if value < 50 else "orange" if value < 80 else "green" if value < 100 else "blue" for value in [100, 80, 60, 50]]
  ...
)