A streamgraph, or stream graph, is a type of stacked

area graph An area chart or area graph displays graphically quantitative data. It is based on the line chart. The area between axis and line are commonly emphasized with colors, textures and hatchings. Commonly one compares two or more quantities with an ar ...

which is displaced around a central axis, resulting in a flowing, organic shape. Unlike a traditional stacked area graph in which the layers are stacked on top of an axis, in a streamgraph the layers are positioned to minimize their "wiggle". More formally, the layers are displaced to minimize the sum of the squared slopes of each layer, weighted by the area of the layer. Streamgraphs display data with only positive values, and are not able to represent both negative and positive values. Streamgraphs and their use were popularized by

Amanda Cox Amanda Cox is an American journalist and head of special data projects at USAFacts. Until January 2022 she was the editor of the ''New York Times'' data journalism section ''The Upshot''. Cox helps develop and teach data journalism courses at th ...

in a February 2008 ''

New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...

'' article on movie box office revenues. Cox got the idea from then-undergraduate Lee Byron, who had used a similar method for visualizing his music listening history. A related graph, sometimes conflated with streamgraphs, is the ThemeRiver, in which the "silhouette" of the graph is symmetrically arranged around the central axis. Streamgraphs were found to be more readable than basic stacked area graphs or ThemeRivers for value comparison tasks. Streamgraphs are officially supported by Matplotlib and

D3.js D3.js (also known as D3, short for Data-Driven Documents) is a JavaScript library for producing dynamic, interactive data visualizations in web browsers. It makes use of Scalable Vector Graphics (SVG), HTML5, and Cascading Style Sheets (CSS) sta ...

. Marco Di Bartolomeo and Yifan Hu (2016) propose several improvements to streamgraphs, such as using 1-norm minimization instead of

2-norm In mathematics, a norm is a function from a real or complex vector space to the non-negative real numbers that behaves in certain ways like the distance from the origin: it commutes with scaling, obeys a form of the triangle inequality, and is z ...

minimization.

References

External links

Lee Byron's streamgraph_generator

RAWGraphs
Open-source visualization tool easing streamgraph generation.
StreamGraph
Open-source javascript for generating a streamgraph in SVG. Diagrams Statistical charts and diagrams {{statistics-stub