Pandas
Notes and Ideas:
- DataFrame is like tabular data structure
- Series is like a 1D array(column) data structure
a = pd.Series([1,2,3,...])
a.type => what data type this column is obtain
len(a) => how many value this column has contain
a.str.lower() # convert uppercases to lowercases
b.str.extract("([A-Z])") # extract the first upper case letter
loc -> label base
iloc -> int positison