Definitely useful! I think we would need us to think about how best to tie this in with the 2D implementation in https://github.com/matplotlib/matplotlib/blob/main/lib/matplotlib/streamplot.py

I'm a little uncomfortable with how we are currently abstracting away all the streamline calculations - there's a lot of nuance about integrator settings that we are brushing under the rug. For example I think using only a 2nd order runge-kutta method right now for integration is a bit of a questionable choice, as is using a linear interpolator, and boundary conditions aren't configurable at all. But the very nature & sparsity of a streamline plot does suggest that it's just an approximate visualization, so maybe this is fine. Shouldn't preclude adding in a basic implementation in any case.

I would start with an external package for this, and then we can see if we can work it in. In particular I would be much more concerned about speed and how to make it look reasonable than accuracy.

@jklymak do you know of an external package for this? I did a quick search but couldn’t find anything. If I recall correctly how it worked with the contour package we pull in, that it started in matplotlib and split off after it got to a point of high enough maturity.

I meant I would suggest writing an external package.

contouring was split off because it is a more general problem than just Matplotlib, and now other libraries can use it. If we were doing it again, I suspect we would have started out that way. Similarly here - calculating streamlines is complex, and somewhat dependent on the underlying physics, so developing the code outside of Matplotlib may make sense, and then we could make it a dependency eventually if there is a simple API that can be used.

Seconding this - I would love a 3D streamplot feature for Matplotlib. Is there any work being done in this direction?

I need a function to draw ternary streamplot. I know a package python-ternary can draw ternary diagrams, but it can't draw stream plot. Can anyone help me?

Some updates to the 2D implementation: #29333