I want to write that graph in matplotlib, but I don't know the name of the graph and I don't know how to search it. In such a case, look at gallery of matplotlib and the answer is You may find it.
There are various graphs like this. For some reason, the COBOL developer, [Grace Hopper](http://en.wikipedia.org/wiki/%E3%82%B0%E3%83%AC%E3%83%BC%E3%82%B9% There is also an example using a photograph of E3% 83% BB% E3% 83% 9B% E3% 83% 83% E3% 83% 91% E3% 83% BC). It is already beyond the scope of the graph. Clicking on the image file in the gallery will take you to the page with the sample code, which is convenient.