Photo of 3D printed tactile Clustered Heatmap
3D printed tactile model of the Clustered Heatmap
Sighted version of the tactile Clustered Heatmap
Sighted version of the tactile Clustered Heatmap

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
  • 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.

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.