Mastering pandas - Second Edition

Operations on indexes

To complete this chapter, we'll discuss operations on indexes. We sometimes need to operate on indexes when we wish to realign our data or select it in different ways. There are various operations:

Note that set_index allows the creation of an index on an existing DataFrame and returns an indexed DataFrame, as we have seen before:

    In [939]: stockIndexDataDF=pd.read_csv('./stock_index_data.csv')
    In [940]: stockIndexDataDF
    Out[940]:   TradingDate  Nasdaq   S&P 500  Russell 2000
      0   2014/01/30   4123.13  1794.19  1139.36
      1   2014/01/31   4103.88  1782.59  1130.88
      2   2014/02/03   3996.96  1741.89  1094.58
      3   2014/02/04   4031.52  1755.20  1102.84
      4   2014/02/05   4011.55  1751.64  1093.59
      5   2014/02/06   4057.12  1773.43  1103.93
  

Now, we can set the index as ...