Heatmap / 2D Surface

This tutorial shows how to configure and customize an Heatmap / 2D Surface layer into ZENPLOT® for your future visualizations.


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1. Data

In this tutorial, we use the faithfuld.csv dataset. It corresponds to the waiting time between two eruptions and their duration for the Old Faithful geyser, located in Yellowstone National Park, in the United States. An estimate of the density of the time and duration variables was calculated. It contains 5,625 observations, described by 3 variables:

  • eruptions, quantitative variable: eruption time in mins
  • waiting, quantitative variable: waiting time to next eruption (in mins)
  • density, quantitative variable: estimated density

Sources:

Härdle, W. (1991). Smoothing Techniques with Implementation in S. New York: Springer. Azzalini, A. and Bowman, A. W. (1990). A look at some data on the Old Faithful geyser. Applied Statistics, 39, 357–365. doi: 10.2307/2347385.

2. Configure an Heatmap / 2D Surface layer into ZENPLOT®

To create an Heatmap / 2D Surface layer, click on Add a layer and select the Heatmap / 2D Surface layer.

Tutorial Heatmap/2D Surface Chart step 1 Tutorial Heatmap/2D Surface Chart step 2

Each observation in the dataset corresponds to a tile, depending on the associated X and Y coordinates. The width and height of the tile correspond to the minimum interval between two values ​​(respectively of X and of Y).

You must enter:

  • The dataset you want to use (here, faithuld)
  • The variable corresponding to the X coordinates of the tiles: a quantitative or qualitative variable
  • The variable corresponding to the Y coordinates of the tiles: a quantitative or qualitative variable

Tutorial Heatmap/2D Surface Chart step 3

3. Customize an Heatmap / 2D Surface layer in ZENPLOT®

Once the Heatmap / 2D Surface layer is created, different options are available in the options bar. You can choose two ways to customize the characteristic of an element:

By imposing a uniform style on all elements

In this case, all the tiles of the layer will have the same style applied for that characteristic (same border or same color).

Tutorial Heatmap/2D Surface Chart step 4

By binding the characteristic to a variable in the dataset

In this case, all the tiles on the layer will have a different style for that characteristic depending on the value they take for the linked variable.

When binding to a qualitative variable, you must choose a style for each category of the variable.

Tutorial Heatmap/2D Surface Chart step 5

When binding to a quantitative variable, it is necessary to define a minimum, median, and maximum value . A gradient is thus produced.

Tutorial Heatmap/2D Surface Chart step 6

3.1 Layer setting

You can reconfigure your layer at any time (change datasets, variables, etc.)

Tutorial Heatmap/2D Surface Chart step 7

3.2 Border options

3 border options are available:

  • Thickness
  • Type
  • Color

In the Heatmap / 2D Surface layer, these characteristics cannot be linked to any variable.

Tutorial Heatmap/2D Surface Chart step 8

3.3 Filling options

Tutorial Heatmap/2D Surface Chart step 9