Skip to main content

sample_arc()

Sample mesh data along a circular arc.

Creates a circular arc probe from pointa to pointb around center with the specified resolution and samples the mesh data onto each point along the arc. For temporal datasets, automatically sweeps all time points unless time_value is specified.

Parameters
  • pointa (Sequence[float]) — Starting point [x, y, z] of the arc.
  • pointb (Sequence[float]) — Ending point [x, y, z] of the arc.
  • center (Sequence[float]) — Center point [x, y, z] of the circle containing the arc.
  • resolution (int, default: 100) — Number of segments to divide the arc into. The resulting arc will have resolution + 1 points.
  • negative (bool, default: False) — If False, the arc spans the positive angle from pointa to pointb around center. If True, spans the negative (reflex) angle.
  • time_value (float | None, default: None) — Query a specific time value instead of sweeping all time points. Ignored for static datasets.
  • tolerance (float | None, default: None) — Tolerance for the sample operation. If None, PyVista generates a tolerance automatically.
Returns

Returns a list of dictionaries (one per time step) with a "time" key and array names as keys. Each array has:

  • For scalars: "distance", "value", "x", "y", "z" (sample point coordinates)
  • For vectors: "distance", "x_value", "y_value", "z_value", "tangential" (component along arc), "normal" (component perpendicular to arc), "x", "y", "z" (sample point coordinates)

For static datasets, returns a single-element list with time 0.0.

[
    # Time 0 (or single time for static)
    {
        "time": 0.0,
        "scalar_name": {
            "distance": [0.0, 0.1, 0.2, ...],
            "value": [val0, val1, val2, ...],
            "x": [x0, x1, x2, ...],
            "y": [y0, y1, y2, ...],
            "z": [z0, z1, z2, ...]
        },
        "vector_name": {
            "distance": [0.0, 0.1, 0.2, ...],
            "x_value": [x0, x1, x2, ...],
            "y_value": [y0, y1, y2, ...],
            "z_value": [z0, z1, z2, ...],
            "tangential": [t0, t1, t2, ...],
            "normal": [n0, n1, n2, ...],
            "x": [x0, x1, x2, ...],
            "y": [y0, y1, y2, ...],
            "z": [z0, z1, z2, ...]
        },
        ...
    },
    # Time 1
    {"time": 0.01, ...},
    ...
]

Examples​

Sweep all time steps​

from pyemsi import Plotter, examples
from matplotlib import pyplot
import numpy as np

file_path = examples.ipm_motor_path()
plt = Plotter(file_path)

data = plt.sample_arc(pointa=(0.080575, 0, 0), pointb=(0.0569751, 0.0569751, 0), center=(0, 0, 0), resolution=100)

time_values = [time_data["time"] for time_data in data]
distances = data[0]["B-Mag (T)"]["distance"]
value_grid = np.array([time_data["B-Mag (T)"]["value"] for time_data in data])
time_grid, distance_grid = np.meshgrid(time_values, distances, indexing="ij")

fig, ax = pyplot.subplots(subplot_kw={"projection": "3d"})
ax.plot_surface(time_grid, distance_grid, value_grid, cmap="viridis")
ax.set_xlabel("Time (s)")
ax.set_ylabel("Distance Along Arc (m)")
ax.set_zlabel("B-Mag (T)")
ax.set_title("B-Mag (T) Along Sampled Arc")
fig.tight_layout()
fig.savefig("docs/static/demos/sample_arc.png")

Sample Arc

Plot three time slices​

from pyemsi import Plotter, examples
from matplotlib import pyplot

file_path = examples.ipm_motor_path()
plt = Plotter(file_path)

data = plt.sample_arc(pointa=(0.080575, 0, 0), pointb=(0.0569751, 0.0569751, 0), center=(0, 0, 0), resolution=100)
time_indices = sorted({0, len(data) // 2, len(data) - 1})

fig, ax = pyplot.subplots()
for idx in time_indices:
    ax.plot(
        data[idx]["B-Mag (T)"]["distance"],
        data[idx]["B-Mag (T)"]["value"],
        label=f"t = {data[idx]['time']:.3f} s",
    )
ax.set_xlabel("Distance Along Arc (m)")
ax.set_ylabel("B-Mag (T)")
ax.set_title("B-Mag (T) Along Sampled Arc at Three Time Points")
ax.legend()
fig.tight_layout()
fig.savefig("docs/static/demos/sample_arc_time_slices.png")

Sample Arc Time Slices

Plot tangential and normal B-Vec components​

from pyemsi import Plotter, examples
from matplotlib import pyplot
import numpy as np

file_path = examples.ipm_motor_path()
plt = Plotter(file_path)

data = plt.sample_arc(pointa=(0.080575, 0, 0), pointb=(0.0569751, 0.0569751, 0), center=(0, 0, 0), resolution=100)
time_indices = sorted({0, len(data) // 2, len(data) - 1})

fig, axes = pyplot.subplots(1, 2, figsize=(12, 4))
component_map = [
    ("tangential", "Tangential B-Vec (T)"),
    ("normal", "Normal B-Vec (T)"),
]

for ax, (component_key, ylabel) in zip(np.atleast_1d(axes), component_map):
    for idx in time_indices:
        ax.plot(
            data[idx]["B-Vec (T)"]["distance"],
            data[idx]["B-Vec (T)"][component_key],
            label=f"t = {data[idx]['time']:.3f} s",
        )

    ax.set_xlabel("Distance Along Arc (m)")
    ax.set_ylabel(ylabel)
    ax.legend()

axes[0].set_title("Tangential Component")
axes[1].set_title("Normal Component")
fig.suptitle("B-Vec (T) Components Along Sampled Arc at Three Time Points")
fig.tight_layout()
fig.savefig("docs/static/demos/sample_arc_bvec_components_time_slices.png")

Sample Arc B-Vec Components Time Slices

See Also​