Rhino.geometry python script error

Grasshopper
,
1

Hi all,

I have created a small script that defined the midpoints based on a input list of points.
I am trying to calculate the distance between all the mid points (d_1,d_2,d_3) and the distance between the first point to the first mid point (m_1), and the distance from the last point to the last mid points (m_2).

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image892×544 11.1 KB

Whenever I calculate the distance m2 I get the following error:

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter ‘index’)
** at Rhino.Runtime.Code.Languages.PythonNet.CPythonCode.Execute(RunContext context)**
** at Rhino.Runtime.Code.Code.ExecTry(RunContext context, IPlatformDocument& doc, Object& docState)**
** at Rhino.Runtime.Code.Code.Run(RunContext context)**

Code:

<
import Rhino.Geometry as rg

# Input parameter
input_points = your_input_points  # Connect your list of points here

# Initialize an empty list to store midpoints
midpoints = []
A = input_points[0]
Z = input_points[-1]

# Compute midpoints between subsequent points
for i in range(len(input_points) - 1):
    point1 = input_points[i]
    point2 = input_points[i + 1]
    midpoint = (point1 + point2) / 2
    midpoints.append(midpoint)

# Initialize a list to store distances between midpoints
distances_between_midpoints = []

# Compute distances between consecutive midpoints
for i in range(len(midpoints) - 1):
    distance_between_midpoints = rg.Point3d.DistanceTo(midpoints[i], midpoints[i + 1])
    distances_between_midpoints.append(distance_between_midpoints)

# Calculate the distance from the first original point to the first midpoint
B = midpoints[0]
distance_to_first_midpoint = A.DistanceTo(B)

# Calculate the distance from the last original point to the last midpoint
C = midpoints[-1]
distance_to_last_midpoint = Z.DistanceTo(C)

# Output the resulting midpoints and distances between midpoints
a = midpoints
b = distances_between_midpoints
c = distance_to_first_midpoint
d = distance_to_last_midpoint>

When I do not consider the distance_to_last_midpoint solution, the script works well.

See Code:

import Rhino.Geometry as rg

# Input parameter
input_points = your_input_points  # Connect your list of points here

# Initialize an empty list to store midpoints
midpoints = []
A = input_points[0]
#Z = input_points[-1]

# Compute midpoints between subsequent points
for i in range(len(input_points) - 1):
    point1 = input_points[i]
    point2 = input_points[i + 1]
    midpoint = (point1 + point2) / 2
    midpoints.append(midpoint)

# Initialize a list to store distances between midpoints
distances_between_midpoints = []

# Compute distances between consecutive midpoints
for i in range(len(midpoints) - 1):
    distance_between_midpoints = rg.Point3d.DistanceTo(midpoints[i], midpoints[i + 1])
    distances_between_midpoints.append(distance_between_midpoints)

# Calculate the distance from the first original point to the first midpoint
B = midpoints[0]
distance_to_first_midpoint = A.DistanceTo(B)

# Calculate the distance from the last original point to the last midpoint
#C = midpoints[-1]
#distance_to_first_midpoint = Z.DistanceTo(C)

# Output the resulting midpoints and distances between midpoints
a = midpoints
b = distances_between_midpoints
c = distance_to_first_midpoint
#d = distance_to_last_midpoint

I guess is somthing to do with the [-1] i use to select the last component of the list, but to me it sound quite wired.

Anywone can help?

Thanks in advance

2

Please edit your post above and format your code for Python

Three backticks plus python
the code
Three more backticks

image

1 Like
3

Thanks for the tip :slight_smile:

4

The error message will tell you the line that raised the exception.

It looks like a basic index out of bounds error.

If your_input_points is None or empty, the script still looks for the first item, which does not exist.

5

That does seem like a Rhino python bug.

There are two things you should do to figure it out.

First, at the beginning check if len(input_points) < 2 and quit if it is.
You need at least 2 input points or your midpoint list will be empty.

Next substitute the -1 indexing with len(X) - 1
like this:
Z = input_points[-1]

becomes

Z = input_points[ len(input_points) - 1]

If that works then yes it is a Rhino Python bug. The error message states that negative numbers are not allowed which also indicates python is not being implemented correctly.

If code still fails then something else is wrong .

1 Like
6

Maybe input_points is not a proper Python list, it may be an Array or some other type.
I’d try to cast it to a list:
something like

input_point_list = list( input_points )

and then use that list in your computations.

HTH

7

It works, thank you very much! :slight_smile: