Retime Timetable
Resample or aggregate timetable data in the Live Editor
Description
The Retime Timetable task lets you interactively change the row times of a timetable and then resample or aggregate the data in its variables. The task automatically generates MATLAB® code for your live script.
Using this task, you can:
Interpolate data values at new row times.
Aggregate data into time bins (for example, to create a timetable containing quarterly means from monthly data).
Remove rows that have duplicate row times.
Make an irregular timetable into a regular one by specifying a uniform time step or sample rate.
Open the Task
To add the Retime Timetable task to a live script in the MATLAB Editor:
On the Live Editor tab, select Task > Retime Timetable.
In a code block in the script, type a relevant keyword, such as
retimeortimetable. Select Retime Timetable from the suggested command completions.
Examples
Resample and Aggregate Timetable Data Using Live Editor Task
The example shows how to resample and aggregate data in a timetable by using the Retime Timetable Live Editor task. You also can apply different rules for adjusting timetable variables in different ways.
Resample Data
Create a timetable using column vectors of data. The row times are between 10 and 50 milliseconds.
Intensity = [100 98.7 95.2 101.4 99.1]'; Time = milliseconds([11 20 34 40.3 49.9])'; TT1 = timetable(Time,Intensity);
Add the Retime Timetable task to your live script. Resample the data in TT.
To specify a sample rate of 100 Hz, use the
Selection methodmenus.To adjust the data in the
Intensityvariable by using linear interpolation, use theGeneral rulemenus.
Aggregate Data
Load a second timetable from the bostonTT MAT-file. This timetable has temperature, wind speed, and rainfall measurements for the city of Boston. The measurements are approximately six hours apart but are irregular.
load bostonTT
Add a second instance of the Retime Timetable task to your live script. Aggregate the data into daily time bins.
To specify a time step of one day, use the
Selection methodmenus.To calculate means of the timetable variables, use the
General rulemenus.To specify a different rule for the
Rainvariable, use theExceptionsmenu. Add an exception to interpolate rainfall measurements at the beginning of each day.
Related Examples
Parameters
Input timetable — Name of timetable
drop-down list item
Specify the name from a list of all the nonempty timetables that are in the workspace.
Selection method — Method for specifying row times
drop-down list item
Specify the method for calculating new row times of the timetable.
Time step— Length of time between consecutive regularly spaced row times.Sample rate— Sample rate or frequency for regularly spaced row times.Times from workspace— Workspace variable that is a vector ofdatetimeordurationvalues. The times in the vector replace the row times of the timetable. The times need not be regularly spaced.
General rule — Rule for adjusting data values
drop-down list item
Specify the rule for resampling or aggregating values in the variables of the timetable. The rule applies to all variables unless exceptions are specified.
Fill values— Fill gaps with missing data indicators or a constant value.Interpolate data— Interpolate data values to the new row times. For example, resample data measured at 100 Hz to 200 Hz.Aggregate data— Aggregate data into time bins. For example, calculate a daily mean from data values measured at every hour.
Exceptions — Different rule or rules for adjusting specified variables
drop-down list item
Click the Add button. Then specify a timetable variable from the drop-down list of variable names that appears.
To adjust the data in the specified variable, select a rule from the drop-down list of rules to the right of the variable name. The rule for the exception can differ from the general rule.
To specify exceptions for other timetable variables, click the + button to the right of the first exception. New drop-down lists of variable names and rules appear below the previous exception.