Spiral Strip Graphic

A visual graphic called Spiral strip is presented. It is loosely based on the warming stripes infographic designed and published by University of Reading climate scientist Ed Hawkings in 2019, which features a minimalistic rectangular design consisting of narrow color-coded vertical segments (stripes) arranged horizontally. The meaning of the graphic is very easy to grasp and can be intuitively understood by a casual observer. By contrast, the Spiral strip consists of color-coded segments arranged in an Archimedian spiral. With spiral geometry, the length of individual segments can be larger compared to the warming stripe, making it easier to display a longer series and provide more textual and numerical information along each segment. Also, the width and length of each individual segment can be different, which can be used to convey additional information (besides the color-coding). In order to avoid the large deformation of segments near the center (which is a typical problem for similarly looking graphics in spiral geometry), a customized coordinate system was used to define the shapes of individual segments, which in turn look less deformed near the center. Although the primary motivation for developing the new graphic was related to climate data, it can also be used with other types of data. Several examples based on climate, population size, and historical data are used to show the graphic's visual appearance and main properties. The examples also demonstrate how the meaning of the new graphics can be easy to grasp and intuitively understood by a casual observer. An easy-to-use python code package for drawing the Spiral strips was published in a public repository.