This is a cryptographic algorithm based on the way text messages were written using cellphones with buttons numbered from 1 to 9, cellphones like Nokia 3310.
It is very simple to understand the algorithm, just ask yourself the following question:
How many times would I hit the button numbered "2" until I get a "c"?
That technique is the algorithm basis, however it is easily extensible using things such as functions to increase the level of security. You can customize it to fit your own needs.
The reason why I call it coordinates' cypher is because of the ' which reminds me of GPS coordinates.
To encode a file, you type python3 main.py -e 'file.extension', the output file will be file.nje
To decode a file, you type python3 main.py -d 'file.nje', the output file will be file.njd
Check the folder example to see the results.