Advanced Python - 2. Containers

Advanced Python - 2. Containers.ipynb

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    "###Data structures - choosing the right tool for the job\n",
    "\n"
   ]
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   "source": [
    "####Scenario 1.\n",
    "\n",
    "Store an ordered collection of employee names. Names are added each time an employee wins a chess game."
   ]
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     "text": [
      "all chess winners in order ['Patrick', 'James', 'James']\n",
      "winner of the second chess game: James\n"
     ]
    }
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   "source": [
    "# list is the perfect choice:\n",
    "# - ordered\n",
    "# - efficient to extend\n",
    "chess_winners = ['Patrick', 'James']\n",
    "chess_winners.append('James') # James is on a winning streak!\n",
    "print('all chess winners in order {}'.format(chess_winners))\n",
    "print('winner of the second chess game: {}'.format(chess_winners[1]))"
   ]
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   "source": [
    "####Scenario 2.\n",
    "\n",
    "Store a collection of employee's who work on a given team"
   ]
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   "execution_count": 2,
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    "# we know that employees should be unique - a set is the natural choice.\n",
    "executive_employees = {'Jack', 'Jill', 'Joan'}\n",
    "dodgeball_employees = {'Carrie', 'Martina', 'Jack'}"
   ]
  },
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   "metadata": {},
   "source": [
    "####Scenario 3.\n",
    "\n",
    "For each location a company operates, store a collection of employee's names.\n",
    "\n",
    "In future you will want to efficiently retrieve a given offices' employees."
   ]
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     "text": [
      "employees working in Bristol are: {'Hannah', 'Joan', 'Jack', 'Martina'}\n"
     ]
    }
   ],
   "source": [
    "# dictionary's are perfect for relationships.\n",
    "# notice we are filling the dictionary in with more sets.\n",
    "employees_in_region = {'london': {'Carrie', 'John', 'Bob', 'Lisa'},\n",
    "                       'leeds': {'Patrick', 'George', 'Martina'},\n",
    "                       'bristol': {'Hannah', 'Jack', 'Martina', 'Joan'}}\n",
    "\n",
    "print('employees working in Bristol '\n",
    "      'are: {}'.format(employees_in_region['bristol']))"
   ]
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   "execution_count": 4,
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     "text": [
      "whos in 'brxxistol'?: None\n"
     ]
    }
   ],
   "source": [
    "# get can be used when you don't want an Exception thrown\n",
    "# when a key is missing...\n",
    "print(\"whos in 'brxxistol'?: {}\".format(employees_in_region.get('brxxistol')))"
   ]
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   "source": [
    "####Scenario 4.\n",
    "\n",
    "Find all the employees that are on the executive team and working in bristol, but don't play dodgeball."
   ]
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   "execution_count": 5,
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   "outputs": [
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     "data": {
      "text/plain": [
       "{'Joan'}"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "# sets make solving relational problems trivial.\n",
    "(employees_in_region['bristol'] & executive_employees) - dodgeball_employees"
   ]
  },
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   "metadata": {},
   "source": [
    "####Scenario 5.\n",
    "\n",
    "Store the state of the battleships board game."
   ]
  },
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   "execution_count": 6,
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   "source": [
    "# classes are simple to define\n",
    "class BattleShip:\n",
    "    \n",
    "    def __init__(self, size):\n",
    "        self.size = size\n",
    "        \n",
    "    def __str__(self):\n",
    "        return \"Ship of size {}\".format(self.size)\n",
    "    \n",
    "# tuples are perfect for storing the ships positions.\n",
    "# they can be used to form compound datastructures. \n",
    "# As long as their contents, are hashable, they are hashable.\n",
    "player1_board = {\n",
    "    (0, 1): BattleShip(2),\n",
    "    (4, 2): BattleShip(5)\n",
    "}\n",
    "\n",
    "player2_board = {\n",
    "    (2, 3): BattleShip(2),\n",
    "    (4, 2): BattleShip(5)\n",
    "}"
   ]
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   "execution_count": 7,
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     "text": [
      "Player 1's board\n",
      "(0, 1): Ship of size 2\n",
      "(4, 2): Ship of size 5\n",
      "\n",
      "Player 2's board\n",
      "(4, 2): Ship of size 5\n",
      "(2, 3): Ship of size 2\n"
     ]
    }
   ],
   "source": [
    "print(\"Player 1's board\")\n",
    "for position in player1_board:\n",
    "    print(\"{}: {}\".format(position, player1_board[position]))\n",
    "    \n",
    "    \n",
    "print(\"\\nPlayer 2's board\")\n",
    "for position in player2_board:\n",
    "    print(\"{}: {}\".format(position, player2_board[position]))"
   ]
  }
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