Examples

This section contains practical examples demonstrating how to use Ngawari for common tasks.

Basic Geometry Example

from ngawari import ftk, fIO, vtkfilters
import numpy as np

# Create a sphere
sphere = vtkfilters.buildSphereSource([0, 0, 0], radius=1.0)

# Get points and add scalar data based on distance from origin
points = vtkfilters.getPtsAsNumpy(sphere)
distances = np.linalg.norm(points, axis=1)
vtkfilters.setArrayFromNumpy(sphere, distances, "distance", SET_SCALAR=True)

# Apply smoothing
smoothed = vtkfilters.smoothTris(sphere, iterations=10)

# Save the result
fIO.writeVTKFile(smoothed, "smoothed_sphere.vtp")

print(f"Created sphere with {smoothed.GetNumberOfPoints()} points")

Clipping Example

from ngawari import ftk, fIO, vtkfilters

# Load or create some data
sphere = vtkfilters.buildSphereSource([0, 0, 0], radius=1.0)

# Clip with a plane
plane_point = [0.5, 0, 0]
plane_normal = [1, 0, 0]  # x-direction
clipped = vtkfilters.clipDataByPlane(sphere, plane_point, plane_normal)

# Clip with a sphere
clip_center = [0.3, 0, 0]
clip_radius = 0.4
final_result = vtkfilters.getPolyDataClippedBySphere(clipped, clip_center, clip_radius)

# Save result
fIO.writeVTKFile(final_result, "clipped_sphere.vtp")

print(f"Clipped sphere has {final_result.GetNumberOfPoints()} points")

Image Data Example

from ngawari import ftk, fIO, vtkfilters
import numpy as np

# Create a simple image data
dims = [50, 50, 50]
spacing = [0.1, 0.1, 0.1]
origin = [0, 0, 0]

image_data = vtkfilters.buildRawImageData(dims, spacing, origin)

# Create some scalar data (example: distance from center)
points = vtkfilters.getPtsAsNumpy(image_data)
center = np.array([2.5, 2.5, 2.5])  # Center of the image
distances = np.linalg.norm(points - center, axis=1)

# Add the data to the image
vtkfilters.setArrayFromNumpy(image_data, distances, "distance_from_center", SET_SCALAR=True)

# Apply median filtering
filtered = vtkfilters.filterVtiMedian(image_data, filterKernalSize=3)

# Save the result
fIO.writeVTKFile(filtered, "filtered_image.vti")

print(f"Created image data with {filtered.GetNumberOfPoints()} points")

Mathematical Operations Example

from ngawari import ftk, fIO, vtkfilters
import numpy as np

# Create some test points
points = np.array([
    [0, 0, 0],
    [1, 0, 0],
    [0, 1, 0],
    [1, 1, 0]
])

# Calculate distances between points
for i in range(len(points)):
    for j in range(i+1, len(points)):
        dist = ftk.distTwoPoints(points[i], points[j])
        print(f"Distance between point {i} and {j}: {dist:.3f}")

# Normalize vectors
vectors = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
normalized = ftk.normaliseArray(vectors)
print("Normalized vectors:")
print(normalized)

# Calculate angles between vectors
angle = ftk.angleBetween2Vec(vectors[0], vectors[1])
print(f"Angle between first two vectors: {angle:.3f} radians")

File I/O Example

from ngawari import ftk, fIO, vtkfilters

# Create some geometry
sphere = vtkfilters.buildSphereSource([0, 0, 0], radius=1.0)
cylinder = vtkfilters.buildCylinderSource([2, 0, 0], radius=0.5, height=2.0)

# Save individual files
fIO.writeVTKFile(sphere, "sphere.vtp")
fIO.writeVTKFile(cylinder, "cylinder.vtp")

# Load them back
loaded_sphere = fIO.readVTKFile("sphere.vtp")
loaded_cylinder = fIO.readVTKFile("cylinder.vtp")

print(f"Loaded sphere has {loaded_sphere.GetNumberOfPoints()} points")
print(f"Loaded cylinder has {loaded_cylinder.GetNumberOfPoints()} points")

# Create a PVD file for time series data
time_data = {
    0.0: sphere,
    1.0: cylinder
}

fIO.writeVTK_PVD_Dict(time_data, ".", "example", ".vtp")
print("Created PVD file for time series data")