Grouper.ipynb

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   "source": [
    "# Initialisation d'une collection Mongo avec 100 documents\n",
    "\n",
    "from pymongo import MongoClient\n",
    "\n",
    "collection = MongoClient().lerni_dev.iterators\n",
    "collection.drop()\n",
    "\n",
    "for i in range(100):\n",
    "    collection.insert({'value': i})"
   ]
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    "# Fonction pour faire des chunks depuis un itérateur\n",
    "# depuis la doc officielle des itérateurs\n",
    "# https://docs.python.org/2/library/itertools.html#recipes\n",
    "\n",
    "from itertools import izip_longest\n",
    "\n",
    "def grouper(iterable, n):\n",
    "    args = [iter(iterable)] * n\n",
    "    return izip_longest(fillvalue=None, *args)"
   ]
  },
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   "cell_type": "code",
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     "text": [
      "('A', 'B', 'C')\n",
      "('D', 'E', 'F')\n",
      "('G', None, None)\n"
     ]
    }
   ],
   "source": [
    "# Exemple simple\n",
    "# Note : tous les chunk ont la même taille\n",
    "# le dernier est rempli avec des None\n",
    "\n",
    "for g in grouper('ABCDEFG', 3):\n",
    "    print g"
   ]
  },
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   "execution_count": 121,
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     "text": [
      "({u'value': 0}, {u'value': 1}, {u'value': 2}, {u'value': 3}, {u'value': 4}, {u'value': 5}, {u'value': 6}, {u'value': 7}, {u'value': 8}, {u'value': 9}, {u'value': 10}, {u'value': 11}, {u'value': 12}, {u'value': 13}, {u'value': 14}, {u'value': 15}, {u'value': 16}, {u'value': 17}, {u'value': 18}, {u'value': 19}, {u'value': 20}, {u'value': 21}, {u'value': 22}, {u'value': 23}, {u'value': 24}, {u'value': 25}, {u'value': 26}, {u'value': 27}, {u'value': 28}, {u'value': 29}, {u'value': 30}, {u'value': 31}, {u'value': 32}, {u'value': 33}, {u'value': 34}, {u'value': 35}, {u'value': 36}, {u'value': 37}, {u'value': 38}, {u'value': 39})\n",
      "\n",
      "({u'value': 40}, {u'value': 41}, {u'value': 42}, {u'value': 43}, {u'value': 44}, {u'value': 45}, {u'value': 46}, {u'value': 47}, {u'value': 48}, {u'value': 49}, {u'value': 50}, {u'value': 51}, {u'value': 52}, {u'value': 53}, {u'value': 54}, {u'value': 55}, {u'value': 56}, {u'value': 57}, {u'value': 58}, {u'value': 59}, {u'value': 60}, {u'value': 61}, {u'value': 62}, {u'value': 63}, {u'value': 64}, {u'value': 65}, {u'value': 66}, {u'value': 67}, {u'value': 68}, {u'value': 69}, {u'value': 70}, {u'value': 71}, {u'value': 72}, {u'value': 73}, {u'value': 74}, {u'value': 75}, {u'value': 76}, {u'value': 77}, {u'value': 78}, {u'value': 79})\n",
      "\n",
      "({u'value': 80}, {u'value': 81}, {u'value': 82}, {u'value': 83}, {u'value': 84}, {u'value': 85}, {u'value': 86}, {u'value': 87}, {u'value': 88}, {u'value': 89}, {u'value': 90}, {u'value': 91}, {u'value': 92}, {u'value': 93}, {u'value': 94}, {u'value': 95}, {u'value': 96}, {u'value': 97}, {u'value': 98}, {u'value': 99}, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None)\n",
      "\n"
     ]
    }
   ],
   "source": [
    "# Exemple avec mongo\n",
    "# Note : ici aussi, le dernier chunk est rempli avec des None\n",
    "\n",
    "cursor = collection.find({}, {'_id': False})\n",
    "\n",
    "for c in grouper(cursor, 40):\n",
    "    print c\n",
    "    print "
   ]
  }
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