Clustered Heatmap Tactile Chart Exploration Instructions
Follow these instructions to explore the tactile model of a clustered heatmap.
Step 1: Orienting the Chart
- Locate the cut corner at the top-right of the board.
- Position the chart so this corner remains at the top-right.
- On the back, there are two stickers:
- A smaller square label near the cut corner contains a QR code. Scanning it with your phone will take you to this companion website.
- A larger rectangular label provides a labeled version of the chart.
Step 2: Introduction to the Clustered Heatmap
- This tactile model represents a clustered heatmap of tabular data.
- Move your hand to the top-left corner to feel the title: "Clustered Heatmap."
- Broadly explore the board to get an overview. The chart is located on the right side of the board.
- This chart type combines a heatmap and dendrograms:
- The Heatmap is a matrix of squares representing data values through heights.
- The Dendrograms are Tree-like diagrams positioned above and to the right of the heatmap, showing the similarity between rows and columns.
- The data:
- This clustered heatmap visualizes how frequently actors appear in different movie genres.
- Similar actors and genres are grouped together.
Step 3: Explore the Heatmap
- Locate the Heatmap: On the right side of the board, find the matrix of squares (the heatmap).
- Rows and Columns:
- Rows represent 5 actors, labeled in Braille on the left side of each row, from top to bottom:
- Dwayne Johnson
- Julia Roberts
- Tom Hanks
- Jennifer Lawrence
- Leonardo DiCaprio
- Columns represent 4 movie genres, labeled in Braille at the bottom of each column using abbreviations, from left to right:
- a: Action
- d: Drama
- c: Comedy
- r: Romance
- Rows represent 5 actors, labeled in Braille on the left side of each row, from top to bottom:
- Legend: On the top-left of the board, below the chart title, find the legend enclosed in a rectangular frame. It explains the column abbreviations.
- Squares:
- Height: The height of the squares encodes the number of movies an actor has performed in in a specific genre. High squares indicate many moves, while lower or flat squares indicate fewer or no movies.
- Braille Numbers: Each square has a Braille number representing its value.
- Example Exploration:
- Top row (Dwayne Johnson), the four squares from left to right:
- Action: Very high (45 movies). This is the highest square in the whole heatmap, so it is the biggest value.
- Drama: Low (10 movies).
- Comedy: Medium-high (28 movies).
- Romance: Flat (0 movies). This is the smallest value in the heatmap.
- Top row (Dwayne Johnson), the four squares from left to right:
Step 4: Exploring the Dendrograms
- Dendrograms show hierarchical grouping based on similarity.
- Row Dendrogram (Actor Clusters):
- Locate the Row Dendrogram: On the right edge of the heatmap, find the tree-like structure.
- From the right end of each row of the heatmap, you'll feel a line extending to the right.
- These lines connect rows to each other and group together hierarchically.
- The more quickly the lines group together, the more similar the two rows are.
- Clusters are groups of similar rows with close connections.
- This chart shows two main clusters among actors.
- Cluster 1: Julia Roberts and Tom Hanks (rows 2 and 3 from top):
- Trace their lines to see how they connect to each other quickly.
- Confirm in the heatmap: Feel the similar height patterns of squares in their rows:
- Both are low in Action (column 1 from left).
- Both are high in Drama and Comedy (columns 2 and 3).
- Both are moderately high in Romance (column 4).
- Cluster 2: Jennifer Lawrence and Leonardo DiCaprio (rows 4 and 5):
- Similarly, trace their lines to see how they group quickly.
- Confirm in the heatmap: Feel the similar height patterns of squares in their rows:
- Both are high in Drama.
- Both are low in other genres.
- Outlier: Rows that deviate from the main clusters are outliers.
- This chart shows one outlier among actors.
- Dwayne Johnson (row 1):
- Trace his line to see how it remains separate for a long time.
- Confirm in the heatmap: The pattern in row 1 differs significantly from other rows.
- For example, row 1 shows a very high value in Action (column 1), while other rows show low values in this column.
- Column Dendrogram (Movie Genre Clusters):
- Locate the Column Dendrogram at the top of the heatmap.
- Lines extend from each column upwards, clustering genres hierarchically.
- Its principle is the same as the row dendrogram, but this time it applies to the genres in the columns.
- Cluster and Outlier:
- The movie genres are clustered incrementally in a step-by-step manner, starting with closely related pairs and gradually incorporating more distinct genres. The tall tree indicates that they are generally not very similar.
- Romance and Comedy (columns 3 and 4 from left): These two genres group together first, indicating they are the most similar movie genres among the four genres in terms of actor involvement patterns.
- Drama (column 2): Joins next.
- Action (column 1): Joins last, being the most distinct genre (outlier).
Recap
- The heatmap displays values using a matrix of raised squares.
- The dendrograms reveal similarity between rows and columns.