Expressive Time Series

When an artist draws or paints a line, the line weight varies with the amount of pressure the artist applies. Even a simple pencil line represents the line path and the line weight at the same time, so the hand-drawn line effectively tracks 3 data streams: the x-value, the y-value, and the p-value, where p stands for pressure.

Based on this observation, we can digitally draw three data series with a single line, simply by varying the line width as we go. Here is an example of TSM stock data from 5 weeks, showing both the Adjusted Closing Price and the Volume of Shares traded.

The line is built from polygons and circles arranged just so the edges make nice “knees”. This helps preserve the flow of the expressive line. We can clearly see how a steep increase in value is associated with a high trading volume. Here is the underlying drawing method:

The link to the processing sample is here. If you want to use this approach in your own work, please credit me, and cheers to more expressive lines from here on out. We developed this method for the “Who Owns the Rain” project for C-Lab in Taipei, Taiwan.

The diagram above chronicles the wind and high water of a major storm in the Baltic Sea on Oct 21, 2023. The wind is represented by the stroke width, and the sea level is on the ordinate. There is a good deal of blank space so one can draw the storm on top or layer photos.