# Extracting mesh regions for gmsh mesh

**URL:** <https://fenicsproject.discourse.group/t/extracting-mesh-regions-for-gmsh-mesh/1125>\
**Category:** mesh\
**Created:** [July 11, 2019, 12:24pm UTC](https://fenicsproject.discourse.group/t/extracting-mesh-regions-for-gmsh-mesh/1125 "2019-07-11T12:24:22Z")\
**Posts on this page:** 1\
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**Author:** ![dokken](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/dokken/32/1560_2.png) [@dokken](https://fenicsproject.discourse.group/u/dokken)\
**Post date:** [July 12, 2019, 2:02pm UTC](https://fenicsproject.discourse.group/t/extracting-mesh-regions-for-gmsh-mesh/1125/2 "2019-07-12T14:02:05Z")

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Hi,  
Your boundary markers are already loaded into the facet function `mf`.  
The line `mf = df.cpp.mesh.MeshFunctionSizet(mesh, mvc)` create the meshfunction that can be used in for instance a measure or Dirichlet-condition:  
`ds_admittance = df.Measure(subdomain=mesh, subdomain_data=mf, subdomain_id=3)`, or  
`bc = DirichletBC(FunctionSpace(mesh, "CG", 1), Constant(1), mf, 3)`

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