# Set Difference results between Points and Tangents

Hi everyone,

A bit of a curious one for you today. I’ve never used ‘sets’ in gh before, so I was tinkering around seeing if they could improve any workflow or script design.

In this example I’ve taken a curve, divided into points, used Cull Nth to remove every Nth point to do something with, the idea being I could use Set Difference to grab the culled items to do something else with.

I applied the same logic to the outputs of Divide: Points, Tangents, and Parameters.
However as you can see, the Tangents output is shorter than the rest.

I realise in this example that I could use something like Cull pattern with 15 trues to 1 false, invert and have the result I want. I’m trying to understand why I might use Sets, and why there is a difference between Points/Parameters and Tangents.

Luke

Set Difference - Tangent count.gh (17.8 KB)

Tangent list have duplicate values, if you try with Cull duplicate points you get the same result

Interesting. If I wanted to, say, draw an SDL from each point using the tangent directionn(perhaps rotated), I might run into problems.

Of course in this example I could use an HFrame or something, there must however be examples where we’d not want duplicate tangent values removed, in order to stay locked with the points originally siphoned off.

More an observation at this point than a critical question, if that’s how Set Difference works.

Thanks for the reply,
Luke

This is math , and tangents are attached to their points , use the points to cull tangents list

This circle of tangents as points

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