alt Hacker NewsuPlot maintainer here. this looks interesting, i'll do a deeper dive soon :)
some notes from a very brief look at the 1M demo:
- sampling has a risk of eliminating important peaks, uPlot does not do it, so for apples-to-apples perf comparison you have to turn that off. see https://github.com/leeoniya/uPlot/pull/1025 for more details on the drawbacks of LTTB
- when doing nothing / idle, there is significant cpu being used, while canvas-based solutions will use zero cpu when the chart is not actively being updated (with new data or scale limits). i think this can probably be resolved in the WebGPU case with some additional code that pauses the updates.
- creating multiple charts on the same page with GL (e.g. dashboard) has historically been limited by the fact that Chrome is capped at 16 active GL contexts that can be acquired simultaneously. Plotly finally worked around this by using https://github.com/greggman/virtual-webgl
> data: [[0, 1], [1, 3], [2, 2]]
this data format, unfortunately, necessitates the allocation of millions of tiny arrays. i would suggest switching to a columnar data layout.
uPlot has a 2M datapoint demo here, if interested: https://leeoniya.github.io/uPlot/bench/uPlot-10M.html
Replies
What I did in a few projects to plot aggregated (resampled) data without loosing peaks was to plot it over an area chart representing the min-max values before aggregating (resampling). It worked pretty well.
Not much to add, but as a very happy uPlot user here - just wanted to say thank you for such an amazing library!!
Is there any techniques using wavelet decomposition to decimate the high frequency component while retaining peaks? I feel like that's a more principled approach than sampling but I haven't seen any literature on it describing the specific techniques (unless the idea is fundamentally unsound which is not obvious to me).
Really appreciate you taking the time to look, Leon - uPlot has been a huge inspiration for proving that browser charts don't have to be slow.
Both points are fair:
1. LTTB peak elimination - you're right, and that PR is a great reference. For the 1M demo specifically, sampling is on by default to show the "it doesn't choke" story. Users can set sampling: 'none' for apples-to-apples comparison. I should probably add a toggle in the demo UI to make that clearer.
2. Idle CPU - good catch. Right now the render loop is probably ticking even when static. That's fixable - should be straightforward to only render on data change or interaction. Will look into it.
Would love your deeper dive feedback when you get to it. Always more to learn from someone who's thought about this problem as much as you have.