Parallel_processing_in_Python.ipynb

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    " * before starting this code, please type \"ipcluster start -n 3\" in the terminal\n",
    "   * `-n 3`: set the number of child processes\n",
    "   * in order to do that, you need to install ipyparallel first. I recommend you to use pip,\n",
    "```\n",
    "pip install ipyparallel\n",
    "```\n"
   ]
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   "cell_type": "code",
   "execution_count": 38,
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     "text": [
      "importing numpy on engine(s)\n",
      "importing collections on engine(s)\n",
      "importing networkx on engine(s)\n"
     ]
    }
   ],
   "source": [
    "from ipyparallel import Client\n",
    "\n",
    "# see https://ipyparallel.readthedocs.org/en/latest/multiengine.html\n",
    "rc = Client()\n",
    "\n",
    "# Generate child processes\n",
    "dview = rc[:]\n",
    "\n",
    "# import modules in the child processes\n",
    "with dview.sync_imports():\n",
    "    import numpy\n",
    "    import collections\n",
    "    import networkx\n",
    "\n",
    "dview.block = False"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {
    "collapsed": true
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   "outputs": [],
   "source": [
    "def mapper(year):\n",
    "    return year, numpy.sqrt(year)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {
    "collapsed": true
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   "source": [
    "year_list = range(1900, 1905+1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {
    "collapsed": false,
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1900, 1901, 1902, 1903, 1904, 1905]\n"
     ]
    }
   ],
   "source": [
    "print year_list"
   ]
  },
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   "cell_type": "code",
   "execution_count": 35,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
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       "True"
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     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "# Run mapper in parallel with N_threads\n",
    "res = dview.map_async(mapper, year_list)\n",
    "\n",
    "dview.wait(res)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {
    "collapsed": false,
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1900 43.5889894354\n",
      "1901 43.6004587132\n",
      "1902 43.6119249747\n",
      "1903 43.6233882224\n",
      "1904 43.6348484585\n",
      "1905 43.6463056856\n"
     ]
    }
   ],
   "source": [
    "for year, year_sqrt in res.get():\n",
    "    print year, year_sqrt    "
   ]
  }
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