done

Author: jmportilla

.ipynb_checkpoints/range()-checkpoint.ipynb

@@ -4,7 +4,202 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "#range()"
+    "#range()\n",
+    "\n",
+    "In this short lecture we will be discussing the range function. We haven't developed a very deep level of knowledge of functions yet, but we can understand the basics of this simple (but extremely useful!) function.\n",
+    "\n",
+    "range() allows us to create a list of numbers ranging from a starting point *up to* an ending point. We can also specify step size. Lets walk through a few examples:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]"
+      ]
+     },
+     "execution_count": 7,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "range(0,10)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "list"
+      ]
+     },
+     "execution_count": 8,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "x =range(0,10)\n",
+    "type(x)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "start = 0 #Default\n",
+    "stop = 20 \n",
+    "x = range(start,stop)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]"
+      ]
+     },
+     "execution_count": 4,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "x"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Great! Notice how it went *up to* 20, but doesn't actually produce 20. Just like in indexing. What about step size? We can specify that as a third argument:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[0, 2, 4, 6, 8, 10, 12, 14, 16, 18]"
+      ]
+     },
+     "execution_count": 5,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "x = range(start,stop,2)\n",
+    "#Show\n",
+    "x"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Awesome! Well thats it...or is it?"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <font color='red'>Python 3 Alert!</font>\n",
+    "\n",
+    "You might have been wondering, what happens if I want to use a huge range of numbers? Can my computer store that all in memory?\n",
+    "\n",
+    "Great thinking! This is a dilemma that can be solve with the use of a generator. For a simplified explanation: A generator allows the generation of generated objects that are provided at that instance but does not store every instance generated into memory.\n",
+    "\n",
+    "This means a generator would not create a list to generate like range() does, but instead provide a one time generation of the numbers in that range. Python 2 has a built-in range generator called xrange(). It is recommended to use xrange() for **for** loops in Python 2. \n",
+    "\n",
+    "The good news is in Python 3, range() behaves as a generator and you don't need to worry about it. Let's see a quick example with xrange()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "0\n",
+      "1\n",
+      "2\n",
+      "3\n",
+      "4\n",
+      "5\n",
+      "6\n",
+      "7\n",
+      "8\n",
+      "9\n"
+     ]
+    }
+   ],
+   "source": [
+    "for num in range(10):\n",
+    "    print num"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "0\n",
+      "1\n",
+      "2\n",
+      "3\n",
+      "4\n",
+      "5\n",
+      "6\n",
+      "7\n",
+      "8\n",
+      "9\n"
+     ]
+    }
+   ],
+   "source": [
+    "for num in xrange(10):\n",
+    "    print num"
    ]
   },
   {