The first online resource I recommend is the official Python tutorial. It covers almost every basics you need to write simple python code. After that, you may need to keep the official Python documentation page in your bookmark. You will revisit Python Library Reference many many times in the future.
If you are taking Coursera Introduction to Bioinformatics Algorithms, you must know this website called 'Rosalind.info'. There is a special section called Python Village where you can practice python coding.
Another useful material to learn Python is on Khan Academy, a similar website as Coursera. You can find their Computer Programming course mainly about Python. It includes not only how to write Python code but also the ideas to write computer programs.
- Python for Data Analysis This is a book written by Pandas author Wes McKinney (twitter @wesmckinn).
Tools to write python codes