Tutorial: Data manipulation

[meta00]

Write a notebook to illustrate data manipulation functions, as follows: 1) One example of splitting the whole data into subsegment using time splitting both ECG and PPG. 2) A example splits data by frequency domain for ECG and PPG. Example uses different argument settings. 3) One example to trim the first and the last n-minute data. 4) One example of before and after removing the unchanged value of the n-continuous second. 5) One example of removing invalid signal data (signal = 0 and other vital signs exceed the normal range). 6) One example of removing invalid signal data using the frequency domain.

[Koaha]

Added a notebook example with the ECG data.

TODO PPG data.

Note: Once implemented cut method, use the cut method for example 4,5,6