Exercise 1:

Exercise 2-5:

Reflection: I really find these exercises helpful to improve my skill of managing data, especially after the experience of participating in the ASA Datafest competition. I found R not that efficient to handle big data over 1 GB size, and I hope I’ll do similar work faster wth the help of Python. Also, using the correct regex is important for the meaning of efficiency, which might not matter for small data, but will mean a lot when handing large size data which needs loops over thousands of times. I’ll do more exercises on other sample data using regex.