#!/usr/bin/env python
# coding: utf-8

# In[1]:


import numpy as np
import dolfin as fe


# In[2]:


mesh = fe.UnitSquareMesh(1, 1)

V0 = fe.FunctionSpace(mesh, "DP", 0)
f0 = fe.Function(V0)
f0.interpolate(fe.Expression("x[0]", degree=1))

V1 = fe.FunctionSpace(mesh, "DP", 1)
f1 = fe.Function(V1)
f1.interpolate(fe.Expression("x[0]", degree=1))

V2 = fe.FunctionSpace(mesh, "P", 1)
f2 = fe.Function(V2)
f2.interpolate(fe.Expression("x[0]", degree=1))

cf = fe.CellFunctionSizet(mesh)
cf.set_all(1)

ff = fe.FacetFunctionSizet(mesh)
ff.set_all(1)


# In[3]:


ff.array()[0] = 2
ff.array()[2] = 3


# In[4]:


ff.array()


# In[6]:


get_ipython().run_line_magic('matplotlib', 'inline')


# In[7]:


import dolfin
import matplotlib.pyplot as plt

def facet_plot2d(facet_func, mesh_edges=True):
    ax = plt.gca()
    x_list = []
    y_list = []
    for facet in dolfin.facets(mesh):
        mp = facet.midpoint()
        x_list.append(mp.x())
        y_list.append(mp.y())
    
    if mesh_edges:
        dolfin.plot(facet_func.mesh())
    plt.scatter(x_list, y_list, s=400, c=facet_func.array(),
                edgecolor='b', linewidths=1)
    plt.colorbar()
    
facet_plot2d(ff)


# In[8]:


facet_plot2d(ff, mesh_edges=False)