intro-to-python/01_elements/02_exercises_for-loops.ipynb

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    "**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Run All*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *after* finishing the exercises to ensure that your solution runs top to bottom *without* any errors. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/main?urlpath=lab/tree/01_elements/02_exercises.ipynb)."
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   "source": [
    "# Chapter 1: Elements of a Program (Coding Exercises)"
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    "The exercises below assume that you have read the [first part <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/01_elements/00_content.ipynb) of Chapter 1.\n",
    "\n",
    "The `...`'s in the code cells indicate where you need to fill in code snippets. The number of `...`'s within a code cell give you a rough idea of how many lines of code are needed to solve the task. You should not need to create any additional code cells for your final solution. However, you may want to use temporary code cells to try out some ideas."
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    "## Simple `for`-loops"
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    "`for`-loops are extremely versatile in Python. That is different from many other programming languages.\n",
    "\n",
    "As shown in the first example in [Chapter 1 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/01_elements/00_content.ipynb#Example:-Averaging-all-even-Numbers-in-a-List), we can create a `list` like `numbers` and loop over the numbers in it on a one-by-one basis."
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    "numbers = [7, 11, 8, 5, 3, 12, 2, 6, 9, 10, 1, 4]"
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    "**Q1**: Fill in the *condition* of the `if` statement such that only numbers divisible by `3` are printed! Adjust the call of the [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) function such that the `for`-loop prints out all the numbers on *one* line of output!"
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    "for number in numbers:\n",
    "    if ...:\n",
    "        print(...)"
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   "source": [
    "Instead of looping over an *existing* object referenced by a variable like `numbers`, we may also create a *new* object within the `for` statement and loop over it directly. For example, below we write out the `list` object as a *literal*.\n",
    "\n",
    "Generically, the objects contained in a `list` objects are referred to as its **elements**. We reflect that in the name of the *target* variable `element` that is assigned a different number in every iteration of the `for`-loop. While we could use *any* syntactically valid name, it is best to choose one that makes sense in the context (e.g., `number` in `numbers`).\n",
    "\n",
    "**Q2**: Fill in the condition of the `if` statement such that only numbers consisting of *one* digit are printed out! As before, print out all the numbers on *one* line of output!"
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    "for element in [7, 11, 8, 5, 3, 12, 2, 6, 9, 10, 1, 4]:\n",
    "    if ...:\n",
    "        print(...)"
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    "An easy way to loop over a `list` object in a sorted manner, is to wrap it with the built-in [sorted() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#sorted) function.\n",
    "\n",
    "**Q3**: Fill in the condition of the `if` statement such that only odd numbers are printed out! Put all the numbers on *one* line of output!"
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    "for number in sorted(numbers):\n",
    "    if ...:\n",
    "        print(...)"
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    "Whenever we want to loop over numbers representing a [series <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/Series_%28mathematics%29) in the mathematical sense (i.e., a rule to calculate the next number from its predecessor), we may be able to use the [range() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-range) built-in.\n",
    "\n",
    "For example, to loop over the whole numbers from `0` to `9` (both including) in order, we could write them out in a `list` like below.\n",
    "\n",
    "**Q4**: Fill in the call to the [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) function such that all the numbers are printed on *one* line ouf output!"
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    "for number in [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]:\n",
    "    print(...)"
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    "**Q5**: Read the documentation on the [range() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-range) built-in! It may be used with either one, two, or three expressions \"passed\" in. What do `start`, `stop`, and `step` mean? Fill in the calls to [range() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-range) and [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) to mimic the output of **Q4**!"
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    "for number in range(...):\n",
    "    print(...)"
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   "source": [
    "**Q6**: Fill in the calls to [range() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-range) and [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) to print out *all* numbers from `1` to `10` (both including)!"
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  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "for number in range(...):\n",
    "    print(...)"
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Q7**: Fill in the calls to [range() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-range) and [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) to print out the *even* numbers from `1` to `10` (both including)! Do *not* use an `if` statement to accomplish this!"
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   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "for number in range(...):\n",
    "    print(...)"
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