# Heatmap Chart

A heatmap is a grid-based chart where each cell sits at the intersection of two categorical variables and is colored according to its numeric value. Color intensity replaces bar length or line position, making patterns across large matrices immediately visible.

Heatmaps excel at revealing patterns, correlations, and outliers across two categorical dimensions.

## Site Earnings Heatmap: Week of Jan 1

### Chart Details
- Chart with 28 data points.
- The chart has 1 X axis displaying categories.
- The chart has 1 Y axis displaying categories.
- Created with Highcharts 12.4.0

### Earnings Data
| Date       | Site                     | Earnings       |
|------------|--------------------------|----------------|
| 2023-01-01 | Cheese Board Plus        | $12,454.00     |
| 2023-01-01 | Cheese Board Plus        | $8,213.34      |
| 2023-01-01 | Cheese Board Plus        | $7,057.88      |
| 2023-01-01 | Cheese Board Plus        | $482.63        |
| 2023-01-01 | Cheese Board Plus        | $23,193.08     |
| 2023-01-01 | Cheese Board Plus        | $11,606.20     |
| 2023-01-01 | Cheese Board Plus        | $6,664.05      |
| 2023-01-01 | Cheese Board Plus        | $991.40        |
| 2023-01-01 | Cheese Board Plus        | $22,947.01     |
| 2023-01-01 | Cheese Board Plus        | $7,097.27      |
| 2023-01-01 | Cheese Board Plus        | $6,388.88      |
| 2023-01-01 | Cheese Board Plus        | $626.55        |
| 2023-01-01 | Cheese Board Plus        | $20,087.49     |
| 2023-01-01 | Cheese Board Plus        | $9,347.85      |
| 2023-01-01 | Cheese Board Plus        | $5,664.62      |
| 2023-01-01 | Cheese Board Plus        | $853.31        |
| 2023-01-01 | Cheese Board Plus        | $17,808.20     |
| 2023-01-01 | Cheese Board Plus        | $9,048.37      |
| 2023-01-01 | Cheese Board Plus        | $6,178.06      |
| 2023-01-01 | Cheese Board Plus        | $878.35        |
| 2023-01-01 | Cheese Board Plus        | $20,060.68     |
| 2023-01-01 | Cheese Board Plus        | $10,637.23     |
| 2023-01-01 | Cheese Board Plus        | $3,906.34      |
| 2023-01-01 | Cheese Board Plus        | $585.94        |
| 2023-01-01 | Cheese Board Plus        | $18,305.53     |
| 2023-01-01 | Cheese Board Plus        | $9,297.12      |
| 2023-01-01 | Cheese Board Plus        | $6,520.66      |
| 2023-01-01 | Cheese Board Plus        | $742.75        |

### When to Use a Heatmap
- **Identify high and low values at a glance** – color makes peaks and troughs stand out across the entire matrix.
- **Show relationships between two categorical variables** – understand how different categories interact based on a shared numeric measure.
- **Detect clusters and outliers** – groups of similar-colored cells reveal concentrations, and isolated bright cells flag anomalies.
- **Visualize large tables** – when a numerical table has too many rows and columns to scan, color encoding makes patterns scannable.
- **Analyze time-based patterns** – with days on one axis and hours on the other, heatmaps are a classic tool for spotting activity patterns.

### Choosing a Color Palette
- **Sequential palettes** – a single hue progressing from light to dark (e.g., light blue → dark blue) works well for data that has a natural low-to-high progression.
- **Diverging palettes** – two contrasting hues meeting at a neutral midpoint (e.g., blue → white → red) highlight deviations above and below a central value, such as positive and negative growth rates.
- **Avoid rainbow palettes** – perceptually uneven color progressions create false visual steps and are harder for colorblind readers.

### When to Avoid a Heatmap
- **Very few data points** – a simple table is more direct when the matrix is small (e.g., 3×3).
- **Exact value comparisons are critical** – color differences are less precise than bar length; use a [bar chart](https://instacharts.io/docs/chart-types/bar-chart/) when exact numbers drive decisions.
- **Negative and positive values without a neutral reference** – use a diverging palette and make the zero point explicit, otherwise mixed-sign data is easy to misread.
- **Unordered categories with no meaningful pattern** – if neither axis has a logical order, the chart may look random regardless of the data.