The charts gallery screen is taken from official example of the charts_flutter package. Full credit is given to the development team of charts_flutter.
A picture is worth a thousand words:-
You can see the data visualization capability of the flutter package by running the code in emulator or simply check out the online charts gallery.
If you are interested to reuse the source code of the screen, please check out the charts branch of the git repository hosted at https://github.com/limcheekin/flutter-widgets-explorer. Feel free to fork the repository and send me pull request.
I'd love to hear from you! :)