An IPython Notebook created to downgrade notebooks which are from version dev 3.0 of IPython to version 2.3 of IPython. I do not guarantee that it will work.

Down_grader.ipynb

{
 "metadata": {
  "name": "",
  "signature": "sha256:8a2c4c2adb058dcd7f2239fcd85190e2800b978c125e37fa6e27d6c0072c7156"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Version 3.0 dev IPython Notebook Downgrader"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "This Notebook is an attempt to make a downgrader for IPython Notebooks written using IPython 3.0 dev to Notebooks that run under version 2.3 of IPython.  It has worked on my test cases but I make no guarantee that it will work.  The original notebook remains intact and the name of the downgraded version has \"_downgraded\" added to it which may be a problem on Windows in a deeply nested directory if the total path exceeds 256 characters."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import json\n",
      "from collections import namedtuple\n",
      "import re\n",
      "\n",
      "def cell_downgrade(cell, language):\n",
      "    \"Attempts to convert a dev 3 cell to version 2.3\"\n",
      "    d_graded = {} # create downgraded cell dictionary\n",
      "    source = cell['source']\n",
      "    if cell['cell_type'] != \"code\":\n",
      "        # Check to see if it should be a heading\n",
      "        if cell['cell_type'] == \"markdown\":\n",
      "            try:\n",
      "                pat = re.compile('#+')\n",
      "                line = source[0]\n",
      "                result = pat.match(line)\n",
      "                if result != None:\n",
      "                    level = result.span()[1]\n",
      "                    line = line[level:]\n",
      "                    line = line.strip()\n",
      "                    if len(source)==1:\n",
      "                        d_graded['cell_type'] = \"heading\"\n",
      "                        d_graded['level'] = level\n",
      "                        source[0] = line\n",
      "                        d_graded['metadata'] = {}\n",
      "                    else:\n",
      "                        d_graded['cell_type'] = \"markdown\"\n",
      "                else:\n",
      "                    d_graded['cell_type'] = \"markdown\"\n",
      "            except:\n",
      "                d_graded['cell_type'] = \"markdown\"\n",
      "        else:\n",
      "            d_graded['cell_type'] = cell['cell_type']\n",
      "        d_graded['source'] = source\n",
      "    else:\n",
      "        d_graded['cell_type'] = \"code\"\n",
      "        d_graded['input'] = source\n",
      "        d_graded['language'] = language    \n",
      "    outputs = []\n",
      "    try:\n",
      "        for output in cell['outputs']:\n",
      "            out_dict = {}\n",
      "            for key, item in output.items():\n",
      "                if key == 'name':\n",
      "                    out_dict['stream'] = item\n",
      "                else:\n",
      "                    out_dict[key] = item\n",
      "            outputs.append(out_dict)\n",
      "        d_graded['outputs'] = outputs\n",
      "    except:\n",
      "        pass\n",
      "    try:\n",
      "        if cell['execution_count'] != None:\n",
      "            prompt = cell['execution_count'] \n",
      "            d_graded['prompt_number'] = prompt\n",
      "    except:\n",
      "        pass\n",
      "    # Convert cell metadata\n",
      "    try:\n",
      "        m_data = {}\n",
      "        for key, item in cell['metadata'].items():\n",
      "            if key == 'collapsed':\n",
      "                # Headings do not have a value for 'collapsed' \n",
      "                if d_graded['cell_type'] != \"heading\":\n",
      "                    d_graded[key] = item\n",
      "                continue\n",
      "            else:\n",
      "                m_data[key] = item\n",
      "        d_graded['metadata'] = m_data\n",
      "    except:\n",
      "        print(\"Error with cell metadata:\")\n",
      "        key = 'metadata'\n",
      "        m_data = cell.__getitem__(key) if cell.__contains__(key) else None\n",
      "        print(m_data)\n",
      "        pass\n",
      "    return d_graded\n",
      "\n",
      "def meta_downgrade(metadata):\n",
      "    d_meta = {}\n",
      "    d_meta['signature'] = metadata['signature']\n",
      "    try:\n",
      "        d_meta['celltoolbar'] = metadata['celltoolbar']\n",
      "    except:\n",
      "        pass\n",
      "    d_meta['name'] = ''\n",
      "    \n",
      "    language = metadata['language_info']['name']\n",
      "    Meta = namedtuple('Meta','metadata language')\n",
      "    output = Meta(d_meta,language)\n",
      "    return output\n",
      "\n",
      "def downgrade(notebook):\n",
      "    d_grade = {}\n",
      "    d_grade['nbformat'] = 3\n",
      "    d_grade['nbformat_minor'] = notebook['nbformat_minor']\n",
      "    m_d_grade = meta_downgrade(notebook['metadata'])\n",
      "    d_grade['metadata'] = m_d_grade.metadata\n",
      "    language = m_d_grade.language\n",
      "    cells = []\n",
      "    for cell in notebook['cells']:\n",
      "        d_cell = cell_downgrade(cell,language)\n",
      "        cells.append(d_cell)\n",
      "    d_grade['worksheets'] = [{'cells':cells, 'metadata':{}}]\n",
      "    \n",
      "    return d_grade\n",
      "\n",
      "def convert2old(filename):\n",
      "    \"Trys to convert a Dev 3 version of an IPython Notebook to version 2.3\"\n",
      "    with open(filename,'r') as f:\n",
      "        json_data = json.load(f)\n",
      "    d_graded = downgrade(json_data)\n",
      "    name = filename.strip('.ipynb')\n",
      "    outputname = name + \"_downgraded.ipynb\"\n",
      "#     print(pr.pformat(d_graded))\n",
      "    with open(outputname,'w') as f:\n",
      "        json.dump(d_graded, f, indent=1, sort_keys=True)\n",
      "    print(\"Downgrade complete.\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "convert2old(\"EMPTY_3.ipynb\")\n",
      "# convert2old(\"Examples.ipynb\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Downgrade complete.\n"
       ]
      }
     ],
     "prompt_number": 2
    }
   ],
   "metadata": {}
  }
 ]
}

EMPTY_3.ipynb