Share Heatmap Defaults

Choose the right default before building a “heatmap” whose real question may be share, area, or distribution.

When to use it

Revenue share chart

When I ask for a heatmap and the wording includes share, distribution, portion, “who is bigger,” or “who takes the largest part,” I want the model to decide whether block area should carry the meaning.

Calendar heatmap

When the grid position is fixed, such as days, hours, matrix cells, or GitHub-style contribution boxes, I want the model to keep the cells the same size and use color only for intensity.

Metric switching

When the same dataset has several time windows or statistical views, such as total, 24 hours, week, month, or year, I want the model to design a clear switch instead of mixing unrelated encodings.

Not for

This is not for choosing among unrelated chart families like bar charts versus line charts, and not for implementing a treemap layout algorithm or CSS details.

What it produces

The key decision is made before implementation: treemap or fixed-grid heatmap.

• Encoding choice: decide whether area represents share or whether every cell stays the same size.
• Treemap default: use proportional area when the business question is “who owns how much of the whole.”
• Grid default: keep fixed cells when the cell position itself is the structure, such as days or matrix rows and columns.
• Metric switch: when several time windows exist, switch both area and color together for the selected metric.
• Self-check: ask whether area alone shows who has the larger share; if not, revisit the encoding.
• Never does: write the treemap algorithm, CSS layout, data fetching, color palette, or validation script for you.

Prerequisites & boundaries

Input needed

A chart request that includes the word heatmap or a similar visualization request, plus enough wording to tell whether share, portion, or distribution is the core question.

Neighboring work

• Choosing between bar, pie, line, and other unrelated chart types stays with ordinary chart-design judgment.
• Implementing treemap layout, coordinates, CSS, or tests stays with the coding model at the moment of implementation.
• Picking colors and scales is separate from the area-versus-color encoding decision.

Out of scope

• Heatmaps with no share or portion meaning.
• Calendar heatmaps, correlation matrices, and fixed row-column grids where size has no business meaning.
• Requests where the word “distribution” means density over a dimension rather than parts of a whole.

Subtle boundary

If the wording is ambiguous, ask one clarifying question: is the chart about each item’s share of the whole, or each item’s own activity or strength?