Add script for extracting data and export to VTK

example/yt/extract_2vtk.py

@@ -0,0 +1,61 @@
+"""
+Purpose:
+    Extracts uniform 3D data from yt datasets and exports them to VTK format
+
+Usage:
+    1. Install the requriments via `pip install yt h5py pyevtk`
+    2. Set up the "fn_in" and "fn_out"
+    3. Adjust the "left_edge" and "right_edge" to the target cube boundaries
+    4. Adjust the "dims" to specify the number of cells in each dimension
+    5. Execute the script via `python extract_2vtk.py`
+
+Requirements:
+    - yt
+    - pyevtk
+    - h5py
+"""
+
+import yt
+from pyevtk.hl import imageToVTK
+
+
+# (1) Set up the input and output files
+#     Note: no extension needed in "fn_out"
+fn_in  = "Data_000000"
+fn_out = "Data_000000_VTK"
+
+
+# (2) Extract data using yt
+ds = yt.load(fn_in)
+
+# (2.1) Define the spatial extent and resolution of the uniform grid
+center     = ds.domain_center
+width      = ds.quan(100, "code_length")
+left_edge  = center - 0.5 * width
+right_edge = center + 0.5 * width
+dims       = [128, 128, 128]
+
+# (2.2) Sample data onto a uniform grid using arbitrary_grid()
+ag = ds.arbitrary_grid(left_edge = left_edge, right_edge = right_edge, dims = dims)
+
+# (2.3) Extract fields and convert to CGS units
+dens  = ag["gas", "density"   ].in_cgs().v
+vel_x = ag["gas", "velocity_x"].in_cgs().v
+vel_y = ag["gas", "velocity_y"].in_cgs().v
+vel_z = ag["gas", "velocity_z"].in_cgs().v
+
+
+# (3) Export cell-centered data to VTK
+#     Note: The origin and spacing are in code units
+origin  = tuple(left_edge.in_units("code_length").v)
+spacing = tuple(width.v / dim  for dim in dims)
+
+imageToVTK(
+    fn_out,
+    origin   = origin,
+    spacing  = spacing,
+    cellData = {
+        "density" : dens,
+        "velocity": (vel_x, vel_y, vel_z)
+    }
+)