Knee point in logistic-like curve about kneed

[arvkevi]

Hi @Gabriel-p, thanks for checking out the repo and posting the issue, I think you found a bug. I will try to fix it in the next couple of days.

[arvkevi]

Hey @Gabriel-p sorry for the delay, I have a working branch and an open PR that identifies the knee in your example at x = 73 using the following arguments:

kl = KneeLocator(x, y, curve="convex", direction="increasing", online=True)

You can try installing from source for now until I get this merged and cut a new release.

[arvkevi]

Sure, @Gabriel-p -- I've been meaning to make proper documentation for this repo for a year now... I hope this explanation will do, for now.

When online=False the first knee point identified is returned regardless of whether it's the local maxima on the difference curve or the global maxima. So the algorithm stops early. When online=True, kneed runs in online mode and "corrects" itself by continuing to overwrite any previously identified knees.

Here's a quick example to show the usage of the parameter.

online=False:

from kneed import KneeLocator
y = [0, 1.0, 1.5, 1.8, 1.9, 2.0, 3.5, 5.0, 7.0, 9.0, 9.5, 9.75, 9.9, 10]
kl = KneeLocator(range(len(y)), y, curve="concave", direction="increasing", online=False)
kl.plot_knee_normalized()

online=True:

kl = KneeLocator(range(len(y)), y, curve="concave", direction="increasing", online=True)
kl.plot_knee_normalized()

[Gabriel-p]

Thank you @arvkevi! I'm not entirely sure what the online argument does. Would you mind explaining what it does a bit more in the README?

[Gabriel-p]

Thank you very much @arvkevi, that explains it clearly.