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query_cells()

Query cell data for multiple cells.

For temporal datasets, automatically sweeps all time points unless time_value is specified. For static datasets, returns values directly.

Parameters
  • cell_ids (list[int]) — The cell IDs to query.
  • block_names (list[str] | str | None, default: None) — Block names for MultiBlock meshes. If str, applies to all cells. If list, must match length of cell_ids. Must be None for single-block meshes.
  • time_value (float | None, default: None) — Query a specific time value instead of sweeping all time points. Ignored for static datasets.
Returns

Returns a list of dictionaries, one per cell ID. Each dictionary has the same structure as query_cell.

[
    {  # cell_ids[0]
        "scalar_name": {"time": [...], "value": [...]},
        "vector_name": {"time": [...], "x_value": [...], "y_value": [...], "z_value": [...]},
        ...
    },
    {  # cell_ids[1]
        ...
    },
    ...
]

Examples​

Sweep all time steps​

from pyemsi import Plotter, examples
from matplotlib import pyplot

file_path = examples.transient_path()
plt = Plotter(file_path)
data = plt.query_cells(cell_ids=[0, 75, 225, 63, 198], block_names=["1", "1", "1", "3", "3"])

fig, axes = pyplot.subplots(2, 1, figsize=(8, 10))

# Block 1
axes[0].plot(data[0]["B-Mag (T)"]["time"], data[0]["B-Mag (T)"]["value"], marker="o", label="Cell ID 0")
axes[0].plot(data[1]["B-Mag (T)"]["time"], data[1]["B-Mag (T)"]["value"], marker="o", label="Cell ID 75")
axes[0].plot(data[2]["B-Mag (T)"]["time"], data[2]["B-Mag (T)"]["value"], marker="o", label="Cell ID 225")
axes[0].set_xlabel("Time (s)")
axes[0].set_ylabel("B-Mag (T)")
axes[0].set_title("B-Mag (T) at Cells in Block 1")
axes[0].legend()

# Block 3
axes[1].plot(data[3]["B-Mag (T)"]["time"], data[3]["B-Mag (T)"]["value"], marker="o", label="Cell ID 63")
axes[1].plot(data[4]["B-Mag (T)"]["time"], data[4]["B-Mag (T)"]["value"], marker="o", label="Cell ID 198")
axes[1].set_xlabel("Time (s)")
axes[1].set_ylabel("B-Mag (T)")
axes[1].set_title("B-Mag (T) at Cells in Block 3")
axes[1].legend()

fig.tight_layout()
fig.savefig("docs/static/demos/query_cells.png")

Query Cells

Query a single time value​

from pyemsi import Plotter, examples

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

# Use time_point_value() to look up the time value for a given index
t = plt.time_point_value(4)   # 0.05  (5th time step, zero-based)

# Query only at that time value instead of sweeping all time steps
results = plt.query_cells(cell_ids=[0, 75, 225], block_names="1", time_value=t)

# Each result has single-element time/value lists
print(results[0]["B-Mag (T)"]["time"])   # [0.05]
print(results[0]["B-Mag (T)"]["value"])  # [0.10771600157022476]
print(results[1]["B-Mag (T)"]["value"])  # [0.09627089649438858]
print(results[2]["B-Mag (T)"]["value"])  # [0.026306699961423874]

See Also​