My free trial subscription on Datacamp is terminated. I could learn a little bit about Python applied to data analysis and obtain this certification:
There were 11 lessons which gave an overview of variables, their types, lists, functions, methods, packages, how to use numpy and its array objects for easy data computation and analysis.
I then started the next course (intermediate level) and could follow 3 more lessons about matplotlib (data visualisation, basic plots such as scatter plots or histograms, and chart customisation). But I had to stop, for my free trial subscription was terminated and the next lessons required a premium account.
It was a pleasure and quite entertaining to learn on Datacamp. The lessons are not boring, with a little bit of theory (a video of around 5min), followed by exercises and live programming with an integrated, web-based interface, with automated checks. Points are granted with an official certification when a full course is completed. However, a premium account at around 30$/month was needed which is not cheap. There are probably more details to be learned in more comprehensive reference books and manuals, but this web-based training offers the same advantages as class or instructor-led training with the advantage that you can follow it at your own pace.