]> https://gitweb.dealii.org/ - dealii.git/commitdiff
Add Jupyter Notebook to demonstrate how to use the python wrappers
authorBruno Turcksin <bruno.turcksin@gmail.com>
Mon, 4 Dec 2017 03:08:37 +0000 (22:08 -0500)
committerBruno Turcksin <bruno.turcksin@gmail.com>
Mon, 11 Dec 2017 00:32:35 +0000 (19:32 -0500)
contrib/python-bindings/notebooks/index.ipynb [new file with mode: 0644]
contrib/python-bindings/notebooks/tutorial-1.ipynb [new file with mode: 0644]

diff --git a/contrib/python-bindings/notebooks/index.ipynb b/contrib/python-bindings/notebooks/index.ipynb
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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Tutorial Notebooks\n",
+    "This page contains a link to every notebook as well as a short explanation on what the notebooks do.\n",
+    "\n",
+    "## tutorial-1\n",
+    "[tutorial-1](https://github.com/dealii/dealii/tree/master/contrib/python-bindings/notebooks/tutorial-1.ipynb) shows how to create a **Triangulation** using the python binding. We also show how to refine the grid, merge two **Triangulations**, and finally how to output the **Triangulation** so that it can be loaded in a C++ code."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}
diff --git a/contrib/python-bindings/notebooks/tutorial-1.ipynb b/contrib/python-bindings/notebooks/tutorial-1.ipynb
new file mode 100644 (file)
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--- /dev/null
@@ -0,0 +1,405 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Tutorial-1\n",
+    "\n",
+    "The first thing to do to use the python wrappers is to import the package. **PyDealII** is only a shell and importing it will only allow you to call\n",
+    "```python \n",
+    "help(PyDealII)\n",
+    "``` \n",
+    "**PyDealII** is composed of two libraries: \n",
+    " - **PyDealII.Debug** which uses the debug version of **deal.II**\n",
+    " - **PyDealII.Release** which uses the release version of **deal.II**\n",
+    " \n",
+    "In this tutorial, we import the debug version of the library as **dealii**."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%matplotlib inline\n",
+    "import PyDealII.Debug as dealii"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We start by creating a 2D **Triangulation** of an hyper cube and we globally refine it twice. You can read the documention of **Triangulation** by typing:\n",
+    "```python\n",
+    "help(dealii.Triangulation)\n",
+    "```\n",
+    "This will show you all the functions associated with **Triangulation** and for each one, you will get a short explanation."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "triangulation = dealii.Triangulation('2D')\n",
+    "triangulation.generate_hyper_cube()\n",
+    "triangulation.refine_global(2)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Now we would like to visualize the mesh that has been created. We can output a _vtu_ file using\n",
+    "```python\n",
+    "triangulation.write('triangulation.vtu', 'vtu')\n",
+    "```\n",
+    "and then use VisIt or Paraview. This is probably what you want to do for a 3D **Triangulation**. However, in this tutorial, we will create a function to plot the result using matplotlib. This will allow us to look at the mesh inside the notebook. To do that we will use _matplotlib_ and _numpy_."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import matplotlib.pyplot as plt\n",
+    "from matplotlib.patches import Polygon\n",
+    "from matplotlib.collections import PatchCollection\n",
+    "import numpy as np"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The function below takes as input a **Triangulation** and a function that is used to define the color scheme. In this function, we loop over all the active cells, get the coordinates of the vertices, and use these coordinates to create polygons that we plot. We can loop over the active cells using\n",
+    "```python\n",
+    "for cell in triangulation.active_cells()\n",
+    "```\n",
+    "Once we have a cell, we can get any vertex using\n",
+    "```python\n",
+    "vertex = cell.get_vertex(i)\n",
+    "```\n",
+    "Since a _vertex_ is a **Point**, we can the coordinates of the **Point** using\n",
+    "```python\n",
+    "x = vertex.x\n",
+    "y = vertex.y\n",
+    "z = vertex.z\n",
+    "```\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def plot_triangulation(triangulation, color_scheme):\n",
+    "    fig, ax = plt.subplots()\n",
+    "    patches = []\n",
+    "    colors = []\n",
+    "    cell_id = 0 \n",
+    "    for cell in triangulation.active_cells():\n",
+    "        quad_vertices = np.zeros((4,2))\n",
+    "        # The shift variable is used to reorder the vertices because\n",
+    "        # deal.II and matplotlib require different ordering\n",
+    "        shift = [0,1,3,2]\n",
+    "        for i in range(4):\n",
+    "            vertex = cell.get_vertex(i)\n",
+    "            quad_vertices[shift[i]][0] = vertex.x\n",
+    "            quad_vertices[shift[i]][1] = vertex.y\n",
+    "        quad = Polygon(quad_vertices, closed=True)\n",
+    "        patches.append(quad)\n",
+    "        colors.append(color_scheme(cell_id, cell))\n",
+    "        cell_id += 1\n",
+    "    p = PatchCollection(patches)  \n",
+    "    p.set_array(np.array(colors))\n",
+    "    ax.add_collection(p, autolim=True)\n",
+    "    ax.autoscale_view()\n",
+    "    plt.show()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We know define a color scheme function and plot the **Triangulation**"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
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ZgJf7dMx8c5\nwF8DR4AfAHvGPfMa7Hk78Ci9d9I8BfzOuGc+xf1+HXgJeIveUfqNwCeBTw48xvv7/z1+MOqfaz+h\nKkkNOp2flpEkrZBxl6QGGXdJapBxl6QGGXdJapBxl6QGGXdJapBxl6QG/R/mmfWnndOcZwAAAABJ\nRU5ErkJggg==\n",
+      "text/plain": [
+       "<matplotlib.figure.Figure at 0x7f24415ba828>"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "def color_sc(cell_id, cell):\n",
+    "    return cell_id\n",
+    "\n",
+    "plot_triangulation(triangulation, color_sc)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Now let's assume that the left half of the domain is composed of a different material than the right half of the domain. We will loop over all the cells and if the abscissa of the cell barycenter is less than 0.5, we will assign zero to the *material_id* of the cell. The others cells will be assigned a *material_id* of one.\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "image/png": "iVBORw0KGgoAAAANSUhEUgAAAXcAAAD8CAYAAACMwORRAAAABHNCSVQICAgIfAhkiAAAAAlwSFlz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\n",
+      "text/plain": [
+       "<matplotlib.figure.Figure at 0x7f24351b8278>"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "for cell in triangulation.active_cells():\n",
+    "    if cell.barycenter().x < 0.5:\n",
+    "        cell.material_id = 0\n",
+    "    else:\n",
+    "        cell.material_id = 1\n",
+    "\n",
+    "def mat_id_color_sc(cell_id, cell):\n",
+    "    return cell.material_id\n",
+    "\n",
+    "plot_triangulation(triangulation, mat_id_color_sc)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We will refine isotropically the cells that have a *material_id* equal to zero and plot the **Triangulation**."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "image/png": "iVBORw0KGgoAAAANSUhEUgAAAXcAAAD8CAYAAACMwORRAAAABHNCSVQICAgIfAhkiAAAAAlwSFlz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\nAAAAAElFTkSuQmCC\n",
+      "text/plain": [
+       "<matplotlib.figure.Figure at 0x7f24350972b0>"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "for cell in triangulation.active_cells():\n",
+    "    if cell.material_id == 0:\n",
+    "        cell.refine_flag ='isotropic'\n",
+    "triangulation.execute_coarsening_and_refinement()\n",
+    "\n",
+    "plot_triangulation(triangulation, color_sc)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We will now show how to merge two **Triangulations**. In order to merge the two **Triangulations**, we will need to move (shift) the second **Triangulation** such that it doesn't overlap with the first one."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "image/png": "iVBORw0KGgoAAAANSUhEUgAAAXcAAAD8CAYAAACMwORRAAAABHNCSVQICAgIfAhkiAAAAAlwSFlz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+      "text/plain": [
+       "<matplotlib.figure.Figure at 0x7f243502add8>"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "triangulation_2 = dealii.Triangulation('2D')\n",
+    "triangulation_2.generate_hyper_cube()\n",
+    "triangulation_2.refine_global(2)\n",
+    "triangulation_2.shift([2.,0.])\n",
+    "\n",
+    "plot_triangulation(triangulation_2, color_sc)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We are now almost ready to merge the **Triangulations**. However, deal.II does not allow us to merge **Triangulations** that have been refined. We can use the *flatten_triangulation* function to create new **Triangulations** that are not refined but this function does not work if the mesh contains hanging nodes. Thus, we need to modify the first triangulation."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "image/png": "iVBORw0KGgoAAAANSUhEUgAAAXcAAAD8CAYAAACMwORRAAAABHNCSVQICAgIfAhkiAAAAAlwSFlz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+      "text/plain": [
+       "<matplotlib.figure.Figure at 0x7f2474278748>"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "flatten_triangulation_1 = dealii.Triangulation('2D')\n",
+    "triangulation.generate_hyper_cube()\n",
+    "triangulation.refine_global(2)\n",
+    "triangulation.flatten_triangulation(flatten_triangulation_1)\n",
+    "flatten_triangulation_2 = dealii.Triangulation('2D')\n",
+    "triangulation_2.flatten_triangulation(flatten_triangulation_2)\n",
+    "triangulation_3 = dealii.Triangulation('2D')\n",
+    "triangulation_3.merge_triangulations(flatten_triangulation_1, flatten_triangulation_2)\n",
+    "\n",
+    "plot_triangulation(triangulation_3, color_sc)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Like expected the second **Triangulation** is moved too far on the right. This mistake can easily fixed by moving *flatten_triangulation_2* to the left and merging the **Triangulations** once again. We can see the advantage of using python over C++. In C++, we would have to recompile and rerun the code while in python we can very easily fix our mistake."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "image/png": "iVBORw0KGgoAAAANSUhEUgAAAXcAAAD8CAYAAACMwORRAAAABHNCSVQICAgIfAhkiAAAAAlwSFlz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\n",
+      "text/plain": [
+       "<matplotlib.figure.Figure at 0x7f2434f4c828>"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "flatten_triangulation_2.shift([-1.,0])\n",
+    "triangulation_3.merge_triangulations(flatten_triangulation_1, flatten_triangulation_2)\n",
+    "\n",
+    "plot_triangulation(triangulation_3, color_sc)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Now that we are done generating the grid, we need to save it in a format that will make it easy to load in our C++ code. This can  be done using the _save_ function python and then using the _Triangulation::load()_ function in C++. The only caveat is that **parallel::distributed::Triangulation** cannot load a grid which has refined cells. Once again this can be fixed by flattening the **Triangulation** (this is not necessary here)."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "triangulation_3.save('merged_triangulation')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The C++ code to load the mesh is\n",
+    "```C++\n",
+    "triangulation.load('merged_triangulation');\n",
+    "```"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "**NOTE**\n",
+    "If the C++ code throws an exception, the error message will be shown. However, if the code segfaults then the kernel will simply be killed. In this case, the easiest way to debug your code is to use gdb to find the problem. This can be done by exporting your notebook as a python code and then typing:\n",
+    "``` bash\n",
+    "gdb python\n",
+    "run my_program.py\n",
+    "```\n",
+    "Below, we show an example of an error message coming from the C++ code."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {},
+   "outputs": [
+    {
+     "ename": "RuntimeError",
+     "evalue": "\n--------------------------------------------------------\nAn error occurred in line <443> of file </home/jovyan/work/dealii/contrib/python-bindings/source/cell_accessor_wrapper.cc> in function\n    dealii::python::PointWrapper dealii::python::CellAccessorWrapper::get_vertex(int) const\nThe violated condition was: \n    i<std::pow(2,dim)\nAdditional information: \n    Requested vertex number 5does not exist. The largest vertex number acceptable is 3\n--------------------------------------------------------\n",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+      "\u001b[0;31mRuntimeError\u001b[0m                              Traceback (most recent call last)",
+      "\u001b[0;32m<ipython-input-12-93dcdab2ba83>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;32mfor\u001b[0m \u001b[0mcell\u001b[0m \u001b[0;32min\u001b[0m \u001b[0mtriangulation\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mactive_cells\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m     \u001b[0mvertex\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mcell\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mget_vertex\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m5\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+      "\u001b[0;31mRuntimeError\u001b[0m: \n--------------------------------------------------------\nAn error occurred in line <443> of file </home/jovyan/work/dealii/contrib/python-bindings/source/cell_accessor_wrapper.cc> in function\n    dealii::python::PointWrapper dealii::python::CellAccessorWrapper::get_vertex(int) const\nThe violated condition was: \n    i<std::pow(2,dim)\nAdditional information: \n    Requested vertex number 5 does not exist. The largest vertex number acceptable is 3\n--------------------------------------------------------\n"
+     ]
+    }
+   ],
+   "source": [
+    "for cell in triangulation.active_cells():\n",
+    "    vertex = cell.get_vertex(5)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

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