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    "# Module 2\n",
    "\n",
    "## Video 5: Program Flow II\n",
    "**Python for the Energy Industry**\n",
    "\n",
    "## Conditionals"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The `if` statement allows you to specify what to do if a condition is true. Let's say you also want to specify what to do if it is not true:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Vessel is named something else\n"
     ]
    }
   ],
   "source": [
    "vessel = \"ROCINANTE\"\n",
    "\n",
    "if vessel == \"QUIXOTE\":            \n",
    "    print('Vessel is named QUIXOTE')\n",
    "    \n",
    "else:\n",
    "    print('Vessel is named something else')  "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Multiple conditions can be checked for using `elif` and `else`. These must immediately follow an `if` statement. `elif` will run the indented code if the previous condition is not true, but some other specified condition is true. `else` will always run if the previous condition is not true."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Vessel is named DON\n"
     ]
    }
   ],
   "source": [
    "vessel = \"DON\"\n",
    "\n",
    "if vessel == \"QUIXOTE\":            \n",
    "    print('Vessel is named QUIXOTE')\n",
    "    \n",
    "elif vessel == \"ROCINANTE\":\n",
    "    print('Vessel is named ROCINANTE')\n",
    "    \n",
    "elif vessel == \"DON\":\n",
    "    print('Vessel is named DON')\n",
    "    \n",
    "else:\n",
    "    print('Vessel is named something else')  "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In this example, the first check is if the vessel name is 'QUIXOTE'. As it is not, a second check is done to see if the name is 'ROCINANTE'. This is true, so no further check is done. "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Loops\n",
    "\n",
    "A loop is used to run a chunk of code multiple times. The number of times may be specified in advance, or it may depend on some condition being true, such as in this example of a `while` loop:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "my_num = 1\n",
      "my_num = 2\n",
      "my_num = 3\n",
      "my_num = 4\n",
      "my_num = 5\n",
      "done\n"
     ]
    }
   ],
   "source": [
    "my_num = 0\n",
    "\n",
    "while my_num < 5:\n",
    "    my_num = my_num + 1\n",
    "    print('my_num =',my_num)\n",
    "    \n",
    "print('done')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "55\n"
     ]
    }
   ],
   "source": [
    "my_num = 1\n",
    "my_sum = 0\n",
    "\n",
    "while my_num <= 10:\n",
    "    my_sum = my_sum + my_num\n",
    "    my_num += 1\n",
    "    \n",
    "print(my_sum)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here the indented code will run over and over, until the condition that `my_num` is less than 5 is no longer true. Because the indented code adds 1 to `my_num` each time, the code block only runs 5 times. Be careful: if you'd forgotten to change the value of `my_num` within the indented code block, the loop would keep on running until you force it to stop!"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### For Loops\n",
    "\n",
    "A `for` loop is a type of loop which iterates over a number of items. For loops are often paired with `range` to iterate over successive numbers:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n"
     ]
    }
   ],
   "source": [
    "for x in range(3):\n",
    "    print(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The usefulness of `for` loops will become more clear in the next video."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Exercise:\n",
    "Use a `for` loop to print the sum of all numbers up to and including 100. You should get 5050."
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
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