Merge branch 'part4'

Conflicts:
	part-4.ipynb

Author: treyhunner

part-4.ipynb

@@ -1,7 +1,7 @@
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  "metadata": {
   "name": "",
-  "signature": "sha256:20f6b02042c480fae323fa6c98332c749bfe323d54bb24066930544c93c73a33"
+  "signature": "sha256:826b0e4b3d39f844b868b8370fcaac110d06dbe6afb167b149a60d16aea5592e"
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  "nbformat": 3,
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@@ -23,7 +23,7 @@
       "\n",
       "Now we're going to learn about list comprehensions.\n",
       "\n",
-      "A list comprehension is kind of like an inside-out for loop.  It makes it easy to do operations on elements in a list and return a new list."
+      "A list comprehension is kind of like a reverse for-loop.  It makes it easy to do operations on elements in a list and return a new list."
      ]
     },
     {
@@ -83,7 +83,7 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Now let's do the same thing with a list comprehension:"
+      "Now let's do the same thing by using a list comprehension instead:"
      ]
     },
     {
@@ -110,7 +110,14 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Let's revisit a problem we've already solved:\n",
+      "Note how our list comprehension is written within the brackets: The for-loop statement is written at the end whereas the action inside of the for-loop is written first: n * n"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Let's revisit a problem we've already solved in Danny's lecture on list:\n",
       "\n",
       "Pick every name from a list that begins with a vowel.\n",
       "\n",
@@ -121,7 +128,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "names = [\"Alice\", \"Bob\", \"Cassie\", \"Diane\", \"Ellen\"]"
+      "names = [\"Danny\", \"Audrey\", \"Rise\", \"Alain\"]"
      ],
      "language": "python",
      "metadata": {},
@@ -147,6 +154,16 @@
      "metadata": {},
      "outputs": []
     },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "vowel_names"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
     {
      "cell_type": "markdown",
      "metadata": {},
@@ -180,9 +197,9 @@
      "source": [
       "## Dictionaries\n",
       "\n",
-      "Unlike lists, dictionaries are indexed by keys.  Dictionaries can be used to represent unordered key-value pairs.  Keys are used for lookup and their values are returned.\n",
+      "Unlike lists, dictionaries are indexed by keys.  Dictionaries can be used to represent unordered key-value pairs.  Keys are unique and are used for looking up values assigned to them.\n",
       "\n",
-      "Let's make an Spanish to English translator.  We'll ignore grammar and just translate word-by-word for now."
+      "Let's make a Spanish to English translator.  We'll ignore grammar and just translate word-by-word for now."
      ]
     },
     {
@@ -269,35 +286,23 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Let's loop over each word in the list and translate each one."
+      "Let's translate each word and save them in the list called translated_words. We'll generate this list by using a list comprehension."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "for spanish_word in sentence_words:\n",
-      "    print(words[spanish_word])"
+      "translated_words = [print(words[spanish_word]) for spanish_word in sentence_words]"
      ],
      "language": "python",
      "metadata": {},
      "outputs": []
     },
-    {
-     "cell_type": "markdown",
-     "metadata": {},
-     "source": [
-      "Now let's make a list from the translated words."
-     ]
-    },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "translated_words = []\n",
-      "for spanish_word in sentence_words:\n",
-      "    translated_words.append(words[spanish_word])\n",
-      "\n",
       "translated_words"
      ],
      "language": "python",
@@ -391,7 +396,7 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "**Extra Credit:** turn the translate function into a single list comprehension."
+      "**Extra Credit:** Try using a list comprehension in the translate function."
      ]
     },
     {
@@ -549,6 +554,14 @@
      "language": "python",
      "metadata": {},
      "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
     }
    ],
    "metadata": {}