add A_setup_python, Cygwin_setup.md, update .gitignore

.gitignore

@@ -128,8 +128,8 @@ dmypy.json
 # Pyre type checker
 .pyre/
 
+
+
 # project-specific files
 README_init.md
-A_setup_python/
 B_explore_python/
-Cygwin_setup.md

A_setup_python/README.md

+# Assignment A: Setup Python &nbsp; (<span style="color:red">12 Pts</span>)
+
+This assignment will setup your base Python enviroment. If you already have it, simply run challenges and answer questions (if any). If you cannot run challenges, set up the needed software.
+
+
+### Challenges
+1. [Challenge 1:](#1-challenge-1-terminal) Terminal
+2. [Challenge 2:](#2-challenge-2-python3) Python3
+3. [Challenge 3:](#3-challenge-3-pip) pip
+4. [Challenge 4:](#4-challenge-4-test-python) Test Python
+5. [Challenge 5:](#5-challenge-5-python-built-in-functions)
+    Python built-in functions
+
+
+&nbsp;
+### 1.) Challenge 1: Terminal
+
+If you are using *MacOS* or *Linux*, skip steps for *Windows*.
+
+For *Windows*,
+
+- Use a Unix emulator such as
+[cygwin](https://www.cygwin.com),
+the built-in Windows Subsystem for Linux
+[WSL](https://learn.microsoft.com/en-us/windows/wsl/install)
+or a
+[Linux VM](https://ubuntu.com/tutorials/how-to-run-ubuntu-desktop-on-a-virtual-machine-using-virtualbox).
+
+    - Windows *CMD.EXE* is no option. *Powershell* is not recommended since it is not compatible with Unix standards.
+
+- Follow
+[instructions](../Cygwin_setup.md)
+for setting up *cygwin*.
+
+Open a terminal and type commands:
+```sh
+> ls -la
+> pwd
+> whoami
+> cat ~/.profile
+> cat ~/.bashrc
+> echo $PATH
+```
+Explain commands. If you are not familiar, find out about these basic Unix shell (bash, zsh, ...) commands (e.g. from [introduction](https://cs.lmu.edu/~ray/notes/bash) or 
+[tutorial](https://linuxconfig.org/bash-scripting-tutorial-for-beginners)).
+
+On *Mac*, refer to file *.zshrc* instead of *.bashrc*.
+
+(4 Pts)
+
+
+&nbsp;
+### 2.) Challenge 2: Python3
+Check if you have Python 3 installed on your system. Name three differences between [Python 2 and 3](https://www.guru99.com/python-2-vs-python-3.html#7). 
+
+Run commands in terminal (exact version 3.x.x may vary):
+```sh
+> python --version
+Python 3.12.0
+```
+(2 Pts)
+
+
+&nbsp;
+### 3.) Challenge 3: pip
+Check if you have a Python package manager installed (pip, conda, ... ). [`pip`](https://pip.pypa.io) is Python's default package manager needed to install additional python packages and libraries.
+
+Follow [instructions](https://pip.pypa.io/en/stable/installing) for installation:
+- [download](https://bootstrap.pypa.io/get-pip.py) the `get-pip.py` file.
+- run `python get-pip.py`
+- or update pip to latest version: `python -m pip install --upgrade pip`
+
+Run commands in terminal:
+```sh
+> pip --version
+pip 23.2.1 from C:\Users\svgr2\AppData\Local\Programs\Python\Python312\Lib\site-
+packages\pip (python 3.12)
+```
+(2 Pts)
+
+
+&nbsp;
+### 4.) Challenge 4: Test Python
+Test Python:
+```py
+> python
+Python 3.12.0 (tags/v3.12.0:0fb18b0, Oct  2 2023, 13:03:39) [MSC v.1935 64 bit (AMD64)] on win32
+Type "help", "copyright", "credits" or "license" for more information.
+
+>>> print('Hello World')
+Hello World
+
+>>> help('modules')
+...lists installed python packages
+
+>>> 2+3*4
+14
+
+>>> x = 2+3*4
+>>> x
+14
+```
+
+Create a file *print_sys.py* with following content.
+```py
+import platform
+
+impl = platform.python_implementation()
+ver = platform.version()
+mach = platform.machine()
+sys = platform.system()
+
+print('Python impl:    ' + impl)
+print('Python version: ' + ver)
+print('Python machine: ' + mach)
+print('Python system:  ' + sys)
+print('Python version: ' + platform.python_version())
+```
+
+Run the file. Output varies depending on your system.
+```
+> python print_sys.py
+Python impl:    CPython
+Python version: 10.0.19045
+Python machine: AMD64
+Python system:  Windows
+Python version: 3.12.0
+```
+(2 Pts)
+
+
+&nbsp;
+### 5.) Challenge 5: Python built-in functions
+Learn about Python's [built-in functions](https://docs.python.org/3/library/functions.html). Test the [*globals()*](https://docs.python.org/3/library/functions.html#globals) function.
+```py
+  >>> globals()
+  {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_
+  importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module
+  'builtins' (built-in)>, 'fruits': ['apple', 'pear', 'orange', 'banana']}
+```
+Test the [*input()*](https://docs.python.org/3/library/functions.html#input) function.
+```py
+  >>> s = input('--> ')
+  --> Monty Python's Flying Circus
+  >>> s
+  "Monty Python's Flying Circus"
+  exit()
+```
+(2 Pts)

A_setup_python/print_sys.py

+import platform
+
+impl = platform.python_implementation()
+ver = platform.version()
+mach = platform.machine()
+sys = platform.system()
+
+print('Python impl:    ' + impl)
+print('Python version: ' + ver)
+print('Python machine: ' + mach)
+print('Python system:  ' + sys)
+print('Python version: ' + platform.python_version())

Cygwin_setup.md

+# Cygwin setup on *Windows*
+
+[Cygwin](https://www.cygwin.com) is a Unix-Emulator that provides
+a terminal in which Unix commands can be executed on Windows 
+using
+[bash](https://en.wikipedia.org/wiki/Bash_(Unix_shell))
+(*Bourne Again Shell*) as command-line interpreter -
+*bash* was developed in 1989 as a successor to the
+*Bourne Shell:*
+*[sh](https://en.wikipedia.org/wiki/Bourne_shell)*.
+
+
+[<bash terminal>](https://cdn.ttgtmedia.com/rms/onlineimages/REF_bash_command_line_3.jpg)
+
+
+*Cygwin* is <span style="text-decoration:underline">not</span>
+a Unix container or virtual machine system (unlike
+[WSL](https://learn.microsoft.com/en-us/windows/wsl/about)).
+*Cygwin* emulates most (not all) Unix system calls such that
+most Unix commands can execute on Windows.
+
+Alternatives to *Cygwin* such as
+[GitBash]()
+can be used, but have some flaws and drawbacks on Windows
+(*GitBash*, for example, performs strange path conversions, see
+[link](https://stackoverflow.com/questions/54258996/git-bash-string-parameter-with-at-start-is-being-expanded-to-a-file-path)).
+
+Good introductions to *bash* are:
+
+- [https://cs.lmu.edu/~ray/notes/bash](https://cs.lmu.edu/~ray/notes/bash).
+
+- Also recommended is the 
+[Tutorial for Beginners](https://linuxconfig.org/bash-scripting-tutorial-for-beginners).
+
+
+&nbsp;
+## Steps
+1. [Installation](#1-installation)
+2. [Configure paths in .bashrc](#2-configure-paths-in-bashrc)
+
+
+&nbsp;
+## 1. Installation
+
+1. Download the installer `setup-x86_64.exe` from
+[https://www.cygwin.com/install.html](https://www.cygwin.com/install.html).
+
+
+1. Run the installer `setup-x86_64.exe`.
+
+    - select useful Unix commands during installation:
+        - Editors/`vim` - visual editor,
+        - Web/`wget` - web downloader,
+        - Net/`curl` - web downloader.
+
+
+1. Change *cygwin* default path `/cygdrive/c` to: `/c`:
+
+    - navigate to the *cygwin* installation directory.
+
+    - inside, edit `/etc/fstab` and replace line
+        ```
+        none /cygdrive cygdrive binary,posix=0,user 0 0
+        with:
+        none / cygdrive binary,posix=0,user 0 0
+        ```
+
+
+1. Add bash-user that works with Windows and create
+   *bash* HOME directory.
+
+    - Find out your Windows user name: <user_name>
+
+    - Create or select a directory that you want to use as
+      HOME-directory for *bash*, e.g. your Windows
+      HOME-directory `C:\Users\<user_name>`.
+
+    - Edit file `/etc/nsswitch.conf`:
+        - to use Windows HOME-directory, comment line
+            ```
+            #db_home:
+            ```
+        - for using a new directory as HOME-directory, enter
+            ```
+            db_home: /cygdrive/c/<path>
+            ```
+
+
+1. Open a new *bash* terminal and test changes:
+
+    ```sh
+    $ whoami
+    <user_name>         # your user name appears
+
+    $ echo $HOME        # print path to HOME-directory
+    <home_directory>    # output, e.g. /c/Users/svgr
+
+    $ cd $HOME          # change into HOME-directory
+    $ ls -la            # show content
+    total 203
+    drwxr-xr-x+ 1 svgr2 Kein      0 Oct  4 22:20 .
+    drwxrwx---+ 1 svgr2 Kein      0 Jan  1  2022 ..
+    -rw-------  1 svgr2 Kein  14476 Oct  4 22:20 .bash_history
+    -rwxr-xr-x+ 1 svgr2 Kein   2717 Oct  4 20:28 .bashrc
+    ...
+
+    $ echo Hello >hello.txt     # create file hello.txt with content Hello
+    $ ls -la                    # show new file exists in $HOME
+    total 203
+    -rw-r--r--  1 svgr2 Kein      6 Oct  7 23:38 hello.txt
+    ...
+
+    $ cat hello.txt             # output content of file
+    Hello
+    ```
+
+
+1. Open Windows file explorer (
+    [ ? ](https://geekflare.com/wp-content/uploads/2021/06/14-alternative-file-managers-to-replace-windows-10-file-explorer.jpg)
+    ) and navigate to file `hello.txt`.
+    Open the file by clicking (ending `.txt` should open the
+    file with *notepad*).
+
+
+1. Return to *bash* terminal:
+    - change to HOME-directory and
+    - open file `.bashrc`
+        ```sh
+        $ cd            # change to bash HOME-directory
+        $ ls -la        # find file .bashrc
+        total 203
+        -rwxr-xr-x+ 1 svgr2 Kein   2717 Oct  4 20:28 .bashrc
+
+        $ cat .bashrc   # output file .bashrc
+        ...
+        ```
+
+
+&nbsp;
+## 2. Configure paths in `.bashrc`
+
+[PATH](https://en.wikipedia.org/wiki/PATH_(variable)) is an
+environment variable on Unix-like operating systems that
+specifys a set of directories where executable programs are
+located. A *"command not found"* error occurs when PATH is
+not properly configured.
+
+1. Open `.bashrc` using an editor, e.g. *vim* and append PATH
+    configurations.
+    ```sh
+    $ vim .bashrc   # open .bashrc in vim editor
+    ```
+
+1. Append PATH configurations at the end of the file - only
+    those relevant on your system - and djust paths for your
+    system:
+
+    ```sh
+    # add Windows system paths
+    export PATH=".:/usr/bin:/usr/local/bin"
+    export PATH="${PATH}:$(cygpath ${SYSTEMROOT}):$(cygpath ${SYSTEMROOT})/system32"
+
+    # add Java path
+    export JAVA_HOME="/c/Program Files/Java/jdk-21"
+    export PATH="${PATH}:${JAVA_HOME}/bin"
+
+    # add Python path
+    export PYTHON_HOME="/c/Users/svgr2/AppData/Local/Programs/Python/Python312"
+    export PATH="${PATH}:${PYTHON_HOME}"
+    export PATH="${PATH}:${PYTHON_HOME}/Scripts"
+
+    # add Docker path
+    export DOCKER_HOME="/c/Program Files/Docker/Docker"
+    export PATH="${PATH}:${DOCKER_HOME}/resources/bin"
+    ...
+    ```
+
+1. Verify paths have been added to *PATH* variable:
+    ```sh
+    $ source .bashrc    # reload .bashrc to activate chances
+    $ echo $PATH                    # show PATH
+    .:/usr/bin:/usr/local/bin:/c/WINDOWS:/c/WINDOWS/system32:/c/Program ...
+
+    $ echo $PATH | tr ':' '\n'      # pretty print PATH
+    .
+    /usr/bin
+    /usr/local/bin
+    /c/WINDOWS
+    /c/WINDOWS/system32
+    /c/Program Files/Java/jdk-21/bin
+    /c/opt/maven/bin
+    /c/Users/svgr2/AppData/Local/Programs/Python/Python312
+    /c/Users/svgr2/AppData/Local/Programs/Python/Python312/Scripts
+    /c/Program Files/Docker/Docker/resources/bin
+    /c/Program Files/MySQL/MySQL Workbench 8.0 CE
+    /c/Program Files (x86)/Git/bin
+    /c/Program Files/Oracle/VirtualBox
+    /c/opt/Qt6/Tools/mingw1120_64/bin
+    /c/opt/Qt6/6.2.4/mingw_64/bin
+    ```
+    Paths may vary based on your system.
+
+
+1. Start programs to verify paths have properly been set.
+
+    ```sh
+    $ java --version
+    java 21 2023-09-19 LTS
+    Java(TM) SE Runtime Environment (build 21+35-LTS-2513)
+    Java HotSpot(TM) 64-Bit Server VM (build 21+35-LTS-2513, mixed mode, sharing)
+
+    $ python --version
+    Python 3.12.0
+
+    $ docker --version
+    Docker version 24.0.6, build ed223bc
+    ```