It's a very good base for your own startig. Sadly you cannot change the width and height of the created picture. It depends on the quantity of the date and the width of the text for the axis, a bit strange. So i insert a x-factor variable, another for the font size and so i can handle the width goog enough for my needs. Added antialiasing for the graph too, looks much better!
But the example and the readme is verey good and helps to get to the point. And the code is clean also! Overall thumbs up after a little pimping ;)