Maths + Divide Curve

Replies to This Discussion

Permalink Reply by Joseph Oster on July 26, 2015 at 7:44pm

I think there might be a subtle error in your description of the problem...?

When I look at your sequence, I see it this way: 1,3,2,3,2,3,2,3,2,3,2,3,2,1 (1/30, 3/30ths, 2/30ths, etc.)

But those add up to 32, not 30.  I didn't see anything about the pattern that inspired me to generate the sequence parameterically, so I moved on to dividing the curve.

1. I entered the sequence of numbers in a 'Panel', parsed them using 'Text Split (Split on comma)', divided the length of the curve by their sum (32 from 'Mass Addition').
2. Multiply each number in the list by that result.  This gives the length of each sub-curve/segment.
3. 'Remap Numbers (ReMap)' lengths from '0 to curve length' to '0..1'.
4. Use 'Series' and 'Sub List (SubSet)' to sum up ('MA') the segment lengths preceding each curve point (0..0, 0..1, 0..2, 0..3, etc.).  These are the 't' values needed for 'Shatter'.
5. 'Flip' the output of 'MA' before passing the list of 't' values to 'Shatter'.  "Flatten' would work here too but experience shows that 'Flip' works better if you want to handle multiple curves.

This works with any sequence of numbers as inputs - integers or floating points.

Attachments:

• Divide_Curve_2015Jul26a.gh, 18 KB

Permalink Reply by Agneesh on July 26, 2015 at 11:59pm

Hello Joseph,

Very kind of you to reply :-). Probably i did not describe my problem properly.

X = total length of original curve. Say for instance X = 1200mm

X/30 = 40mm is repeated 2 times i.e. at the start & end

X/10 = 120mm is repeated 6 times (but alternates with X/15)

X/15 = 80mm is repeated 5 times (alternates with X/10)

So if you add (2x40) + (6x120) + (5x80) = 1200mm this should hold true for any integer.

The way i have tried to resolve is

weave repeat data X/10 6 times, X/10 5 times and weave the data. then insert X/30 as item 0. Then shatter the curve.

However, i was wondering if there was a formula and more straightforward way to handle it :-D

Permalink Reply by Pieter Segeren on July 27, 2015 at 4:50am

Hi Agneesh, not sure if this can be called straightforward but here's my two cents.

* = (2*x)-1

Attachments:

• ShatterPattern_PSG.gh, 22 KB

Permalink Reply by Joseph Oster on July 27, 2015 at 6:56am

Pieter, I like the way you think!

I hadn't noticed the 'Partial Results (Pr)' output of 'Mass Addition' - that is very handy and simplifies my code:

Attachments:

• Divide_Curve_2015Jul26b.gh, 20 KB

Permalink Reply by Joseph Oster on July 27, 2015 at 6:37am

OK, silly me.  I included an extra "2" in my sequence.  Change the panel to this:

1,3,2,3,2,3,2,3,2,3,2,3,1

At first, I did the same thing you did using 'Repeat Data', but I didn't see the point of going to the trouble since it wasn't easily adaptable to other patterns.  Hence my choice of the panel with a sequence of numbers that represent ratios of the line segments to each other.

As usual, Pieter's solution (below) is incredibly elegant and to the point!

Permalink Reply by Pieter Segeren on July 27, 2015 at 8:23am

N.B.: the parameter on the curve domain is not the same as (or directly comparable to) the distance along the curve. You'll need the EvaluateLength component to find the correct parameters.
Do a search for curve parameter length and you'll find dozens of discussions, some of which with a clear explanation.

Permalink Reply by Joseph Oster on July 27, 2015 at 9:06am

"N.B."?  I thought "newbie" was one word?

You must be talking to me(?) because I can see the error I made using 'ReMap', correlating lengths to 't' values.  My bad, thank you.  (I knew better)

Revised:

Attachments:

• Divide_Curve_2015Jul27a.gh, 22 KB

Permalink Reply by Pieter Segeren on July 27, 2015 at 9:53am

Haha - you're joking, right?
It stands for 'nota bene', which is Latin for 'note well'.

So I didn't call you a newbie, grasshopper.  ;) 

Permalink Reply by Agneesh on July 27, 2015 at 4:56pm

Joseph & Pieter thanks for your inputs.

This is a wonderful community and very helpful members.

Pieter, i have used repeat data > weave > insert > shatter

but your definitions is 1 step less and relatively more refined.

Thanks for that.

AB

Permalink Reply by Joseph Oster on July 28, 2015 at 8:16am

I tried applying this solution in another thread (How to divide a circle in segments of 2 different lengths) and discovered an off-by-one error in the previous code! An unnecessary 'Shift' that resulted in one fewer segments than expected. Don't know how I missed this...

Attachments:

• Divide_Curve_2015Jul28a.gh, 18 KB