fixed notebook for Part 2 - Section 4 - Example 1

Author: fbaptiste

Part 2/Section 04 - Iterables and Iterators/04 - Example 1 - Consuming Iterators Manually.ipynb

@@ -21,7 +21,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Let's quickly see how to do this again, using a string as the underlying iterable:"
+    "Let's quickly see how do this again, using a string as the underlying iterable:"
    ]
   },
   {
@@ -91,7 +91,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "A fairly typical use case for this would be when reading data from a CSV file where you know the first few lines consist of information about the data rather than just the data itself.\n",
+    "A fairly typical use case for this would be when reading data from a CSV file where you know the first few lines consist of information abotu teh data rather than just the data itself.\n",
     "\n",
     "Let's try this using a CSV file I have saved alongside the Jupyter notebook."
    ]
@@ -953,7 +953,7 @@
     "Here's what we want to do: \n",
     "* read the first line to get the column headers and create a named tuple class\n",
     "* read data types from second line and store this so we can cast the strings we are reading to the correct data type\n",
-    "* read the data rows and parse them into named tuples"
+    "* read the data rows and parse them into a named tuples"
    ]
   },
   {
@@ -1735,7 +1735,6 @@
     "with open('cars.csv') as file:\n",
     "    file_iter = iter(file)\n",
     "    headers = next(file_iter).strip('\\n').split(';')\n",
-    "    Car = namedtuple('Car', headers)\n",
     "    data_types = next(file_iter).strip('\\n').split(';')\n",
     "    cars_data = [cast_row(data_types, \n",
     "                          line.strip('\\n').split(';'))\n",
@@ -1803,7 +1802,6 @@
     "with open('cars.csv') as file:\n",
     "    file_iter = iter(file)\n",
     "    headers = next(file_iter).strip('\\n').split(';')\n",
-    "    Car = namedtuple('Car', headers)\n",
     "    data_types = next(file_iter).strip('\\n').split(';')\n",
     "    cars = [Car(*cast_row(data_types, \n",
     "                          line.strip('\\n').split(';')))\n",
@@ -1829,302 +1827,6 @@
    "source": [
     "cars[0]"
    ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "#### Example 2"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "Here's another example - suppose we have a loop that iterates over some range of integers. As we loop through those integers we want to create a tuple containing the integer and a string that cycles over a finite set (smaller than the list of integers).\n",
-    "\n",
-    "```\n",
-    "1, 2, 3, 4, 5, 6, 7, 8, 9, ...\n",
-    "\n",
-    "N, S, W, E\n",
-    "```\n",
-    "\n",
-    "and we want to generate\n",
-    "\n",
-    "```\n",
-    "1N, 2S, 3W, 4E, 5N, 6S, 7W, 8E, 9N, ...\n",
-    "```\n"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "We could do it this way by creating a custom iterator for the list `['N', 'S', 'W', 'E']` that will cycle over that list indefinitely:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 23,
-   "metadata": {
-    "collapsed": true
-   },
-   "outputs": [],
-   "source": [
-    "class CyclicIterator:\n",
-    "    def __init__(self, lst):\n",
-    "        self.lst = lst\n",
-    "        self.i = 0\n",
-    "        \n",
-    "    def __iter__(self):\n",
-    "        return self\n",
-    "    \n",
-    "    def __next__(self):\n",
-    "        result = self.lst[self.i % len(self.lst)]\n",
-    "        self.i += 1\n",
-    "        return result"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 24,
-   "metadata": {
-    "collapsed": true
-   },
-   "outputs": [],
-   "source": [
-    "iter_cycl = CyclicIterator('NSWE')"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 25,
-   "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "N\n",
-      "S\n",
-      "W\n",
-      "E\n",
-      "N\n",
-      "S\n",
-      "W\n",
-      "E\n",
-      "N\n",
-      "S\n"
-     ]
-    }
-   ],
-   "source": [
-    "for i in range(10):\n",
-    "    print(next(iter_cycl))"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "So, now we can tackle our original problem:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 26,
-   "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "1N\n",
-      "2S\n",
-      "3W\n",
-      "4E\n",
-      "5N\n",
-      "6S\n",
-      "7W\n",
-      "8E\n",
-      "9N\n",
-      "10S\n"
-     ]
-    }
-   ],
-   "source": [
-    "n = 10\n",
-    "iter_cycl = CyclicIterator('NSWE')\n",
-    "for i in range(1, n+1):\n",
-    "    direction = next(iter_cycl)\n",
-    "    print(f'{i}{direction}')"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "And re-working this into a list comprehension:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 27,
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "text/plain": [
-       "['1N', '2S', '3W', '4E', '5N', '6S', '7W', '8E', '9N', '10S']"
-      ]
-     },
-     "execution_count": 27,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
-   "source": [
-    "n = 10\n",
-    "iter_cycl = CyclicIterator('NSWE')\n",
-    "[f'{i}{next(iter_cycl)}' for i in range(1, n+1)]"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "Of course, there's an easy alternative way to do this as well, using:\n",
-    "* repetition\n",
-    "* zip\n",
-    "* a list comprehension"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "We need to repeat the array ['N', 'S', 'W', 'E'] for as many times as we have elements in our range of integers - we can even create way more than we need - because when we `zip` it up with the range of integers, the smallest length iterable will be used:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 28,
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "text/plain": [
-       "[(1, 'N'),\n",
-       " (2, 'S'),\n",
-       " (3, 'W'),\n",
-       " (4, 'E'),\n",
-       " (5, 'N'),\n",
-       " (6, 'S'),\n",
-       " (7, 'W'),\n",
-       " (8, 'E'),\n",
-       " (9, 'N'),\n",
-       " (10, 'S')]"
-      ]
-     },
-     "execution_count": 28,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
-   "source": [
-    "n = 10\n",
-    "list(zip(range(1, n+1), 'NSWE' * (n//4 + 1)))"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 29,
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "text/plain": [
-       "['1N', '2S', '3W', '4E', '5N', '6S', '7W', '8E', '9N', '10S']"
-      ]
-     },
-     "execution_count": 29,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
-   "source": [
-    "[f'{i}{direction}'\n",
-    " for i, direction in zip(range(1, n+1), 'NSWE' * (n//4 + 1))]"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "There's actually an even easier way yet, and that's to use our `CyclicIterator`, but instead of building it ourselves, we can simply use the one provided by Python in the standard library!!"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 30,
-   "metadata": {
-    "collapsed": true
-   },
-   "outputs": [],
-   "source": [
-    "import itertools"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 31,
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "text/plain": [
-       "['1N', '2S', '3W', '4E', '5N', '6S', '7W', '8E', '9N', '10S']"
-      ]
-     },
-     "execution_count": 31,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
-   "source": [
-    "n = 10\n",
-    "iter_cycl = CyclicIterator('NSWE')\n",
-    "[f'{i}{next(iter_cycl)}' for i in range(1, n+1)]"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "and using itertools:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 32,
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "text/plain": [
-       "['1N', '2S', '3W', '4E', '5N', '6S', '7W', '8E', '9N', '10S']"
-      ]
-     },
-     "execution_count": 32,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
-   "source": [
-    "n = 10\n",
-    "iter_cycl = itertools.cycle('NSWE')\n",
-    "[f'{i}{next(iter_cycl)}' for i in range(1, n+1)]"
-   ]
   }
  ],
  "metadata": {