Retime and Synchronize Timetable Variables Using Different
Methods
This example shows how to fill in gaps in timetable variables, using different methods for different
variables. You can specify whether each timetable variable contains continuous or discrete data using
the VariableContinuity property of the timetable. When you resample the timetable using the
retime function, retime either interpolates, fills in with previous values, or fills in with missing data
indicators, depending on the values in the VariableContinuity property. Similarly, the
synchronize function interpolates or fills in values based on the VariableContinuity property of
the input timetables.
Create Timetable
Create a timetable that has simulated weather measurements for several days in May 2017. The
timetable variables Tmax and Tmin contain maximum and minimum temperature readings for each
day, and PrecipTotal contains total precipitation for the day. WXEvent is a categorical array,
recording whether certain kinds of weather events, such as thunder or hail, happened on any given
day. The timetable has simulated data from May 4 to May 10, 2017, but is missing data for two days,
May 6th and May 7th.
Date = [datetime(2017,5,4) datetime(2017,5,5) datetime(2017,5,8:10)]';
Tmax = [60 62 56 59 60]';
Tmin = [44 45 40 42 45]';
PrecipTotal = [0.2 0 0 0.15 0]';
WXEvent = [2 0 0 1 0]';
WXEvent = categorical(WXEvent,[0 1 2 3 4],{'None','Thunder','Hail','Fog','Tornado'});
Station1 = timetable(Date,Tmax,Tmin,PrecipTotal,WXEvent)
Station1=5×4 timetable
Date
Tmax
Tmin
PrecipTotal
WXEvent
___________
____
____
___________
_______
04-May-2017
60
44
0.2
Hail
05-May-2017
62
45
0
None
08-May-2017
56
40
0
None
09-May-2017
59
42
0.15
Thunder
10-May-2017
60
45
0
None
Resample Continuous and Discrete Timetable Variables
One way to fill in data for the two missing days is to use the retime function. If you call retime
without specifying a method, then retime fills in gaps with missing data indicators. For instance,
retime fills gaps in numeric variables with NaN values, and gaps in the categorical variable with
undefined elements.
Station1Daily = retime(Station1,'daily')
Station1Daily=7×4 timetable
Date
Tmax
Tmin
PrecipTotal
WXEvent
___________
____
____
___________
___________
04-May-2017
60
44
0.2
Hail
05-May-2017
62
45
0
None
06-May-2017
NaN
NaN
NaN

07-May-2017
NaN
NaN
NaN

10 Timetables
10-14