Mastering pandas - Second Edition

Frequency conversion

Time series usually comes with a fixed frequency, for example, every microsecond, every second, every minute, and so on. These frequencies can be changed from one to another.

We can use the asfreq function to change frequencies, as shown in the following snippet:

    In [131]: # Frequency conversion using asfreq
              ibmTS.asfreq('BM')
    Out[131]: 1959-06-30    448
        1959-07-31    428
        1959-08-31    425
        1959-09-30    411
        1959-10-30    411
        1959-11-30    428
        1959-12-31    439
        1960-01-29    418
        1960-02-29    419
        1960-03-31    445
        1960-04-29    453
        1960-05-31    504
        1960-06-30    522
        Freq: BM, Name: closingPrice, dtype: float64
  

In this case, we just obtain the values corresponding to the last day of the month from the ibmTS time series. Here, bm stands for business month ...