import vtk

import python_vtk.vtkService.vtkService as vtkService

x = [1, 2, 3, 4]
y = [1, 2, 3, 4]
ugrid = vtk.vtkUnstructuredGrid()
points = vtk.vtkPoints()
points.SetDataTypeToDouble()
xyToNode = [[] for i in range(len(x))]
index = 0
for i, xCoord in enumerate(x):
    for yCoord in y:
        points.InsertNextPoint(xCoord, yCoord, 0.0)
        xyToNode[i].append(index)
        index += 1
ugrid.SetPoints(points)

# Add the volume elements
for i, xCoord in enumerate(x[:-1]):
    for j, yCoord in enumerate(y[:-1]):
        idList = vtk.vtkIdList()
        idList.InsertNextId(xyToNode[i][j])
        idList.InsertNextId(xyToNode[i + 1][j])
        idList.InsertNextId(xyToNode[i + 1][j + 1])
        idList.InsertNextId(xyToNode[i][j + 1])
        ugrid.InsertNextCell(vtk.VTK_QUAD, idList)

vtkService.writevtk(ugrid, "abc.vtu")
vtkService.writeDataArrayToNewVtkFile("abc.vtu", "var", [1., 2., 3., 4., 5., 6., 7., 8., 9.], "abc_var.vtu")