http://www.th7.cn/Program/Python/201602/770045.shtml
dfdf['1'].value_counts()
dfdf.plot(kind="line", x="1", y="2")
dfdf.plot(kind="scatter", x="1", y="2")
http://web.stanford.edu/~mwaskom/software/seaborn/installing.html
http://web.stanford.edu/~mwaskom/software/seaborn/installing.html
http://blog.youkuaiyun.com/jinruoyanxu/article/details/51000009
http://pandas.pydata.org/pandas-docs/stable/missing_data.html