linux_course_doc/modules/qualifying/exercise_python.md

# Scripting exercises - sorting files

Damn it, I made a mess of my files!
Can you sort the following picture collections for me please?
I don't really care what ordering system you use but thousands of files in one directory is **not** practical.
There are four different folders with files to sort and each one is a **separate** assignment so at the end I expect **four** folders with **sorted** files (and subdirectories).

The files are archived and can me downloaded [here](./assets/files.tar.gz).
I advise you to keep a copy of the archive so you can run your scripts multiple times until you achieve a desirable outcome.

## The batches

### Simple filenames

The first batch of files has a very straight forward filename `FUJI_20120103_171310.jpg`.
The pictures span multiple years but are all from one single device (FUJI).
Sort however you want but `$YEAH/$MONTH` might be a good start.

### Multiple cameras and formats

The second batch has pictures form multiple cameras as well as multiple file extensions.
You can sort in multiple ways but for example `$YEAR/$CAMERA/$MONTH` or `$CAMERA/$YEAR/$MONTH`.
The choice is yours.

### Messy filenames

The third batch is very messy and has not only multiple cameras and formats but also multiple date structures.
This one will require some hefty debugging to parse the datetime strings!

### Recovery files

The fourth batch is pretty messed up.
No dates or logic can be found in the filenames but luckily jpg files can contain **metadata** about the files.
This challenge will require you to search and install extra Python3 libraries to access this metadata.
Installing will be done via `pip3` which comes with Pycharm.
Have a look at this [library](https://github.com/TNThieding/exif) and figure out how to use it.
It might be handy to install `imagemagick` via `sudo apt install imagemagick`.
This gives you the ability to inspect metadata on the Linux command line via `identify -verbose BJtpWU7n7WCeOL2B84Vz.jpg`.
I left the file extension on purpose to make it a bit easier but in the last exercise you'll have to live without so maybe try not relying on the extension to prepare yourself.

### Music metadata

This batch is similar to the previous batch but instead of photo's it's a bunch of mp3's.
As with photo's mp3's have metadata in them do help with sorting in programs like iTunes.
There are multiple libraries out there to read and write these tags with Python3 but none come installed by default.
I can recommend [eyed3](https://eyed3.readthedocs.io/en/latest/) to parse the metadata.
Here it makes little sense to sort via date so maybe sort by `$ARTIST/$ALBUM`.
As an added bonus you could rename the mp3's by their track number instead of the cryptic string the have.

### Mixed filetypes

This one is very tricky.
It's a mix of photo's and mp3's and the extensions are missing!
You'll have to figure out how to determine the filetype before reading the metadata *or* have a deep dive into `try except` statements in Python3.

## Some hints and tips

While we *just* discovered the creation of our own objects in Python3 you don't *need* your own classes to complete these exercises.
I would advise to create multiple **functions** and use a lot of `print()` calls to help you make sense of your `for file in files:` loops.
You can slow down the loops with `time.sleep(1)` if the cycling feels to quick to you.
You can make one script for each batch, or reuse the same script but create different functions for the four batches, whatever is easiest for you.
Ask for **help** from your classmates when you're stuck.
By explaining your problem to someone else you often come up with a solution.

Now some links and phrases to google:

* to **manipulate dates** in Python3, your best bet is the [datetime](https://docs.python.org/3/library/datetime.html) library
* definitely have a look at the [strptime](https://stackabuse.com/converting-strings-to-datetime-in-python) **method** of a datetime object
* paths can be manipulated easily with **two different** [libraries](https://www.reddit.com/r/Python/comments/l45ojr/ospath_vs_pathlib/), os **or** pathlib
* files can be **moved** with multiple [libraries](https://stackoverflow.com/questions/8858008/how-to-move-a-file) as well