chaquopy | Chaquopy: the Python SDK for Android | SDK library

Your Java code isn't actually running any Python script. Check the Chaquopy documentation for examples of how to do that.

Also, your script won't work, because on Android, the current directory is usually the root directory, which is unwritable by normal apps. Instead, as described here, you should write to os.environ["HOME"], which is set to your app's internal storage directory.

If you look more carefully you'll probably see that os.getcwd is returning "/", i.e. the root directory. This is not writable in a normal app, and may not be readable either on some devices.

For advice on where to keep your data files, see the Chaquopy FAQ sections "Read files in Python" and "Write files in Python".

If all you're doing is making TCP or UDP connections, and you're not attempting to use a local port number below 1024, then you won't need root access. However, you will need the INTERNET permission.

If decoded_data is already a complete image file, then I don't see why you need to use NumPy or OpenCV. Just send it to the socket directly:

Pandas added support for the string dtype in version 1.0. So change the pip section of your build.gradle file to install pandas==1.3.2, which we released for Chaquopy a few days ago.

Here, we are giving the python.exe local path

This only affects the build process: this path is not used at runtime. In fact, it couldn't be used at runtime even if we wanted to, because an Android app has no direct access to the filesystem of your computer, even when you're using an emulator.

However, to make it easier for other developers to build your source code, it would be better to remove the buildPython line and allow Chaquopy to find Python on the PATH, as it says in the documentation. If you installed Python from python.org using the default settings, then the py launcher will already be on the PATH, so this will work automatically.

chaquopy is not listed in the dependencies too

That's no problem: the Chaquopy plugin at the top of the file will add any necessary dependencies.

It looks like Pattern doesn't actually require mysqlclient: in fact, it defaults to using SQLite. So you can modify it to remove the requirement:

• Download the sdist from https://pypi.org/project/Pattern/#files.
• Extract it.
• Edit Pattern-3.6/setup.py to remove the "mysqlclient" requirement.
• Create a .zip or .tar.gz file from the modified Pattern-3.6 directory.
• Install this file by its filename, as shown in the Chaquopy documentation.

"COM4" looks like a Windows serial port name, so that won't work on Android. Try using something like serial.tools.list_ports to discover the correct name.

Also, even if you do use the correct name, your app probably still won't have permission to access the port directly. If you're running on a rooted device, you may be able to get pyserial to work by changing the permissions on the port's device file. On non-rooted devices, the only option I know of is to use the Java UsbManager instead, perhaps with the help of a library like UsbSerial. You can still call these APIs from Python with the help of the Chaquopy Python API.

difflib is part of the standard library, so there's no need to install it with pip.