[meshlib] function to get the difference of two meshes

ogstools/meshlib/__init__.py

 from .boundary import Boundary, Layer, LocationFrame, Raster
 from .boundary_set import LayerSet
 from .boundary_subset import Surface
+from .data_processing import difference
 from .gmsh_meshing import cuboid, rect
 from .mesh_series import MeshSeries
 
@@ -12,6 +13,7 @@ __all__ = [
     "Boundary",
     "MeshSeries",
     "LayerSet",
+    "difference",
     "rect",
     "cuboid",
 ]

ogstools/meshlib/data_processing.py

+from typing import Union
+
+import pyvista as pv
+
+from ogstools.propertylib import Property, presets
+
+
+def difference(
+    mesh1: pv.UnstructuredGrid,
+    mesh2: pv.UnstructuredGrid,
+    mesh_property: Union[Property, str],
+) -> pv.UnstructuredGrid:
+    """
+    Compute the difference between two meshes based on a specified property.
+
+    :param mesh1: The first mesh to be subtracted from.
+    :param mesh2: The second mesh whose data is subtracted from the first mesh.
+    :param mesh_property: The property to of interest.
+    :returns: A new mesh representing the difference between mesh1 and mesh2.
+    """
+    if isinstance(mesh_property, str):
+        data_shape = mesh1[mesh_property].shape
+        mesh_property = presets.get_preset(mesh_property, data_shape)
+    diff_mesh = mesh1.copy(deep=True)
+    diff_mesh[mesh_property.data_name] -= mesh2[mesh_property.data_name]
+    return diff_mesh