Lin Ma questions

• find lines in one file but not in another file in Linux Shell
• pandas inner join performance issue
• calculate the differences between two rows in SQL
• decode string algorithm implementation for advice
• Python 2.7 store duplicate string or not
• regular expression match issue in Python
• confusion on 2 dimension kernel density estimation in R
• pandas import error using Pycharm
• object play not found in scala application
• thresholds in roc_curve in scikit learn

Lin Ma answers