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    "# Conditional Statements\n",
    "\n",
    "A conditional statement is a programming concept that describes whether a region of code runs based on if a condition is true or false. The keywords involved in conditional statements are `if`, and optionally `elif` and `else`.\n",
    "\n",
    "## The `if` Statement\n",
    "\n",
    "A conditional statement starts with the `if` keyword, followed by the condition to check, and ends with a `:`. After the `:` is an indented block of code that will only run if the condition evaluates to a value of `True`. For example,"
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     "text": [
      "Temperature is above freezing.\n"
     ]
    }
   ],
   "source": [
    "temperature = 35\n",
    "if temperature > 32:\n",
    "    print('Temperature is above freezing.')"
   ]
  },
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   "source": [
    "The code above is checking whether the value of the variable `temperature` is greater than 32, the freezing point of water in degrees Fahrenheit at mean sea level pressure. If the condition is true, the program prints \n",
    "\n",
    "    Temperature is above freezing. \n",
    "\n",
    "Note the `>` is the greater-than \"operator\" in the usual arithmetic sense. If the condition evaluates to `False`, then the code in the indented block is not executed. We can check the results by looking at the value of the condition, as we do here:"
   ]
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       "True"
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    "temperature > 32"
   ]
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   "source": [
    "We see that the value of the condition is `True`, which explains why the print function was called. We can change the value of `temperature` to see what happens if the condition is `False`:"
   ]
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    "temperature = 30\n",
    "if temperature > 32:\n",
    "    print('Temperature is above freezing.')"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In this example, nothing is printed since the value of `temperature` is not greater than 32. What do we do if we want to run one part of the code if a condition is true, and another if the condition is false? We can make use of the `else` keyword.\n",
    "\n",
    "## The Optional `else` Block\n",
    "\n",
    "To run code if a condition is false, we employ the `else` keyword. The `else` part of the code is created by following the indented code of an `if` statement by an unindented `else:`, followed by an indented block of code. This `else` block of code will execute if the condition in the `if` statement evaluates to `False`. For example, going back to the code we examined earlier, we can augement it to print the message \n",
    "\n",
    "`Temperature is at or below freezing.` \n",
    "\n",
    "in the `else` block for the case where the condition is `False` (i.e., `temperature` is not greater than 32):"
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     "text": [
      "Temperature is at or below freezing.\n"
     ]
    }
   ],
   "source": [
    "temperature = 30\n",
    "if temperature > 32:\n",
    "    print('Temperature is above freezing.')\n",
    "else:\n",
    "    print('Temperature is at or below freezing.')"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The Optional `elif` Block(s)\n",
    "\n",
    "The `if` and `else` keywords are adequate when you have a binary choice such as examining a temperature value that is above or below freezing, but consider a scenario where you want more options. In this case, you will employ the `elif` keyword that will follow the same `:`, indented code block syntax. There can be zero or more `elif` keywords in an `if` statement. Let's write code that will categorize maximum sustained winds in units of knots according to the [Saffir–Simpson hurricane intensity scale](https://en.wikipedia.org/wiki/Saffir%25E2%2580%2593Simpson_scale)."
   ]
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   "execution_count": 5,
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     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Category one hurricane\n"
     ]
    }
   ],
   "source": [
    "wind_speed = 65\n",
    "\n",
    "if wind_speed >= 64 and wind_speed <= 82:\n",
    "    print('Category one hurricane')\n",
    "elif wind_speed >= 83 and wind_speed <= 95:\n",
    "    print('Category two hurricane')\n",
    "elif wind_speed >= 96 and wind_speed <= 112:\n",
    "    print('Category three hurricane')\n",
    "elif wind_speed >= 113 and wind_speed <= 136:\n",
    "    print('Category four hurricane')\n",
    "elif wind_speed > 136:\n",
    "    print('Category five hurricane')\n",
    "else:\n",
    "    print('Below hurricane level wind speed')"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Note, the `>=` arithmetic \"operator\" signifies greater than or equal, and the `<=` means less than or equal. We are also using the `and` keyword to describe a range of values. E.g., `wind_speed >= 64 and wind_speed <= 82` describes the range of values between `64` and `82` knots, end points inclusive. Also, observe that if the `wind_speed` value does not meet any of the `if` or `elif` choices, the code ends up executing the `else` block. For example, a `wind_speed` of `15` will print:\n",
    "\n",
    "    Below hurricane level wind speed."
   ]
  }
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