Forum Discussion
Convex hull Lambda > would it be impossible to build?
Hello everyone, Ever since visiting the site of Andy Pope, I saw a chart that fascinated me because it can be very useful for creating the bounding area of a set of points. It's known as Convex ...
I did. After some discussion with it, it came up with this:
=LAMBDA(points,
LET(
leftmost_point, MIN(points, 1),
x_values, INDEX(points, 0, 1),
y_values, INDEX(points, 0, 2),
n, ROWS(points),
indices, SEQUENCE(n),
indices_sorted, SORTBY(indices, x_values),
upper_hull_indices, FILTER(indices_sorted, y_values >= LINEST(y_values, x_values,,TRUE)),
lower_hull_indices, FILTER(indices_sorted, y_values < LINEST(y_values, x_values,,TRUE)),
upper_hull_points, INDEX(points, upper_hull_indices),
lower_hull_points, INDEX(points, lower_hull_indices),
upper_hull_sorted, SORTBY(upper_hull_points, y_values, -1),
lower_hull_sorted, SORTBY(lower_hull_points, y_values),
upper_hull_final, IF(COUNT(upper_hull_sorted) > 1,
TRANSPOSE({INDEX(upper_hull_sorted, 1),INDEX(upper_hull_sorted,2)}) ,
upper_hull_sorted),
lower_hull_final, IF(COUNT(lower_hull_sorted) > 1,
TRANSPOSE({INDEX(lower_hull_sorted, 1),INDEX(lower_hull_sorted,2)}) ,
lower_hull_sorted),
hull_points, SORTBY(TRANSPOSE({leftmost_point, upper_hull_final, lower_hull_final}), x_values)
,
TEXTJOIN(",",TRUE,hull_points)
))
=LAMBDA(points,
LET(
leftmost_point, MIN(points, 1),
x_values, INDEX(points, 0, 1),
y_values, INDEX(points, 0, 2),
n, ROWS(points),
indices, SEQUENCE(n),
indices_sorted, SORTBY(indices, x_values),
upper_hull_indices, FILTER(indices_sorted, y_values >= LINEST(y_values, x_values,,TRUE)),
lower_hull_indices, FILTER(indices_sorted, y_values < LINEST(y_values, x_values,,TRUE)),
upper_hull_points, INDEX(points, upper_hull_indices),
lower_hull_points, INDEX(points, lower_hull_indices),
upper_hull_sorted, SORTBY(upper_hull_points, y_values, -1),
lower_hull_sorted, SORTBY(lower_hull_points, y_values),
upper_hull_final, IF(COUNT(upper_hull_sorted) > 1,
TRANSPOSE({INDEX(upper_hull_sorted, 1),INDEX(upper_hull_sorted,2)}) ,
upper_hull_sorted),
lower_hull_final, IF(COUNT(lower_hull_sorted) > 1,
TRANSPOSE({INDEX(lower_hull_sorted, 1),INDEX(lower_hull_sorted,2)}) ,
lower_hull_sorted),
hull_points, SORTBY(TRANSPOSE({leftmost_point, upper_hull_final, lower_hull_final}), x_values)
,
TEXTJOIN(",",TRUE,hull_points)
))
Convincing perhaps, but Excel doesn't like the {INDEX(upper_hull_sorted, 1),INDEX(upper_hull_sorted,2)} bits in there.
No, expressions aren't allowed in literal arrays {...}, only constant values.
- Yes. And because I couldn't enter the formula I gave up having real work to do rather than fool around chatting with am artificial intelligence. Lets put Actual Intelligence to work!
Afraid to generate correct answer with AI tool you need more knowledge formulating proper questions rather than to generate the formula by your own from scratch.
