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    "# Module 2\n",
    "\n",
    "## Video 7: Generating Lists\n",
    "**Python for the Energy Industry**\n",
    "\n",
    "It's common to make a list by conditionally appending inside a loop. See this example of making a list of even numbers:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0, 2, 4, 6, 8, 10]\n"
     ]
    }
   ],
   "source": [
    "evens = []\n",
    "\n",
    "for i in range(11):\n",
    "    if i % 2 == 0:\n",
    "        evens.append(i)\n",
    "        \n",
    "print(evens)"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here's another example, of finding the words in a list beginning with A:\n",
    "\n",
    "*Note: strings can be treated in many ways as a list of characters - see below how we access the first letter of word as word[0]*"
   ]
  },
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   "cell_type": "code",
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   "metadata": {},
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     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['AARDVARK', 'APPLE', 'ARROW']\n"
     ]
    }
   ],
   "source": [
    "words = ['AARDVARK','APPLE','ARROW','BARN','CACTUS']\n",
    "a_words = []\n",
    "\n",
    "for word in words:\n",
    "    if word[0] == 'A':\n",
    "        a_words.append(word)\n",
    "        \n",
    "print(a_words)"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This procedure is so common that there is a Python shorthand for it, called the 'list comprehension' which takes the form:\n",
    "\n",
    "``` new_list = [item for item in old_list if condition] ``` \n",
    "\n",
    "Here's how this looks for our even numbers example:"
   ]
  },
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   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0, 2, 4, 6, 8, 10]\n"
     ]
    }
   ],
   "source": [
    "evens = [i for i in range(11) if i % 2 == 0]\n",
    "\n",
    "print(evens)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You can also apply a function onto the item before storing it in the list. We will cover functions in more detail later, but here is a simple example:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0, 4, 16, 36, 64]\n"
     ]
    }
   ],
   "source": [
    "squares = [i**2 for i in range(10) if i % 2 == 0]\n",
    "\n",
    "print(squares)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Exercise\n",
    "\n",
    "Try to write the list comprehension corresponding to our A words example."
   ]
  },
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   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
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