A Stream graph is really close from a stacked area chart. It displays the evolution of a numerical value (Y axis) following another numerical value (X axis). This evolution is represented for several groups, all with a distinct color. Contrary to
a stacked area, there is no corner: edges are rounded what gives this nice impression of flow. Stream chart get really useful when displayed in an interactive mode: highlighting a group gives you directly an insight of its
evolution. Unfortunately, there is no good tool in my knowledge to realise stream chart. Feel free to propose an example if you have one. I highly recommend to have a look to the R graph gallery to find a solution.
Do you know a tool?