intro-to-python/03_conditionals_review_and_exercises.ipynb

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   "source": [
    "\n",
    "# Chapter 3: Conditionals & Exceptions"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Content Review"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Read [Chapter 3](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/master/03_conditionals.ipynb) of the book. Then work through the eight review questions."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Essay Questions "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Answer the following questions briefly with *at most* 300 characters per question!"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q1**: What is the **singleton** design pattern? How many objects does the expression `[True, False, True, False]` generate in memory?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q2**: What do we mean when we talk about **truthy** and **falsy** expressions?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q3**: Describe in your own words the concept of **short-circuiting**! What does it imply for an individual sub-expression in a boolean expression?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q4**: Explain how the conceptual difference between a **statement** and an **expression** relates to the difference between a **conditional statement** and a **conditional expression**."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q5**: Why is the use of **temporary variables** encouraged in Python?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q6**: What does the `finally`-clause enforce in this code snippet? How can a `try` statement be useful *without* an `except`-clause?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```python\n",
    "try:\n",
    "    print(\"Make a request to a service on the internet\")\n",
    "finally:\n",
    "    print(\"This could be clean-up code\")\n",
    "```"
   ]
  },
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   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### True / False Questions"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Motivate your answer with *one short* sentence!"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q7**: The objects `True`, `False`, and `None` represent the idea of *yes*, *no*, and *maybe* answers in a natural language.\n",
    "\n",
    "Hint: you also respond with a code cell."
   ]
  },
  {
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   "metadata": {},
   "source": [
    " "
   ]
  },
  {
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   "metadata": {},
   "source": [
    "**Q8**: The `try` statement is useful for handling **syntax** errors."
   ]
  },
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   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Coding Exercises"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Discounting Customer Orders"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q9.1**: Write a function `discounted_price()` that takes the positional arguments `unit_price` (of type `float`) and `quantity` (of type `int`) and implements a discount scheme for a line item in a customer order as follows:\n",
    "\n",
    "- if the unit price is over 100 dollars, grant 10% relative discount\n",
    "- if a customer orders more than 10 items, one in every five items is for free\n",
    "\n",
    "Only one of the two discounts is granted, whichever is better for the customer.\n",
    "\n",
    "The function should then return the overall price for the line item. Do not forget to round appropriately."
   ]
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  {
   "cell_type": "code",
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   "source": [
    "def discounted_price(...):\n",
    "    ..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q9.2**: Calculate the final price for the following line items of an order:\n",
    "- $7$ smartphones @ $99.00$ USD\n",
    "- $3$ workstations @ $999.00$ USD\n",
    "- $19$ GPUs @ $879.95$ USD\n",
    "- $14$ Raspberry Pis @ $35.00$ USD"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "discounted_price(...)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "discounted_price(...)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "discounted_price(...)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "discounted_price(...)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q9.3**: Calculate the last two line items with order quantities of $20$ and $15$. What do you observe?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "discounted_price(...)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "discounted_price(...)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q9.4**: Looking at the `if`-`else`-logic in the function, why do you think the four example line items in **Q9.2** were chosen as they were?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Fizz Buzz"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The kids game [Fizz Buzz](https://en.wikipedia.org/wiki/Fizz_buzz) is said to be often used in job interviews for entry-level positions. However, opinions vary as to how good of a test it is (cf., [source](https://news.ycombinator.com/item?id=16446774)).\n",
    "\n",
    "In its simplest form, a group of people starts counting upwards in an alternating fashion. Whenever a number is divisible by $3$, the person must say \"Fizz\" instead of the number. The same holds for numbers divisible by $5$ when the person must say \"Buzz.\" If a number is divisible by both numbers, one must say \"FizzBuzz.\" Probably, this game would also make a good drinking game with the \"right\" beverages."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q10.1**: First, create a list `numbers` with the numbers from 1 through 100. You could type all numbers manually, but there is, of course, a smarter way. The built-in [range()](https://docs.python.org/3/library/functions.html#func-range) may be useful here. Read how it works in the documentation. To make the output of [range()](https://docs.python.org/3/library/functions.html#func-range) a `list` object, you have to wrap it with the [list()](https://docs.python.org/3/library/functions.html#func-list) built-in (i.e., `list(range(...))`)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "numbers = ..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q10.2**: Loop over the `numbers` list and replace numbers for which one of the two (or both) conditions apply with text strings `\"Fizz\"`, `\"Buzz\"`, or `\"FizzBuzz\"` using the indexing operator `[]` and the assignment statement `=`.\n",
    "\n",
    "In [Chapter 1](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/master/01_elements.ipynb), we saw that Python starts indexing with `0` as the first element. Keep that in mind.\n",
    "\n",
    "So in each iteration of the `for`-loop, you have to determine an `index` variable as well as check the actual `number` for its divisors.\n",
    "\n",
    "Hint: the order of the conditions is important!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for number in numbers:\n",
    "    ..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q10.3**: Create a loop that prints out either the number or any of the Fizz Buzz substitutes. Do it in such a way that we do not end up with 100 lines of output here."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for number in numbers:\n",
    "    print(...)"
   ]
  }
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