GH and Rhino flip curves problem

I met a problem when I use the GH flip curve, I want all the curves’ direction the same as the guide curve, but I don’t know why the outcome is not what I want,I also use the rhino command MatchCrvDir ,but the outcome is also not always right. So what’s the principle of the flip curve?How it works when to flip the curve?

flip curve.3dm (192.4 KB)


The file has been uploaded.

Some of your curves are not planar, so you’ll need a proper base plane for projection to compare the directions of your curves with your guide curve.

Flip Curve (96.9 KB)

You can also use this by using circle fit from center points and derivatives to create guides

flip (94.1 KB)

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Good ways!Thank you!