How to creat graphs/plots in Drupal, using python library matplotlib, updated in real time if possible?
I don't think there is an out-of-the-box solution for this. You probably already found the Charts module, but that does not seem to support on the fly updates.

So you would need to create your own module. You could then send your data with an ajax call and redraw the graph using that data  (the form api in Drupal 7 has excellent support for this; create a fieldset with its own div in which you put the graph). I'm working with Highcharts (which I really like) in my own modules and do something similar.