MATLAB: What is Matlab equivalent of C++ ros::Duration()

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The way we call ros::Duration in C++, I need to call in Matlab. What its equivalent expression in MATLAB?

Best Answer

As given in ros::Duration Class Reference, the duration object is created as:

ros::Duration five_seconds(5.0); //Duration of 5 seconds

A similar object can be created in MATLAB using 'duration' function:

>> d = duration(0,0,5)
d = 
     00:00:05
>> d2 = duration(0,0,4)
d2 = 
     00:00:04
>> d-d2
ans = 
     00:00:01

The duration function here is of form duration(hour, minute, second). Other ways to use duration can be found here:

http://www.mathworks.com/help/matlab/ref/duration.html

Related Solutions

MATLAB: How to convert timestamps to number of seconds

What do you mean by "number of seconds" ? The number of seconds from when? From what epoch? (without an epoch it is meaningless to count seconds).

The definition of MATLAB's serial date number is clearly defined: "the number of days from January 0, 0000". If you want this time in seconds then simply multiply the serial date number by the number of seconds in a day. Note that these numbers will be much larger!

If you only need the seconds component of those timestamps, then use datevec, and take a look at the sixth column of data:

>> C = {'2013-01-01 00:00:00' '2013-01-01 00:00:01' '2013-01-01 00:00:02'};
>> V = datevec(C)
V =
   2013      1      1      0      0      0
   2013      1      1      0      0      1
   2013      1      1      0      0      2
>> V(:,6)
ans =
   0
   1
   2

MATLAB: Devide a table in several tables by criteria

You can do this in several ways, but honestly the most straight-forward is to write a loop, as shown below. The real question is, why do you want to do this? I'm genuinely asking, because there are tools that let you do things like hourly means without splitting the data up. I guess your answer would be, "I want to plot things separately". Fair enough: you can trick rowfun into doing that but it's a little tricky. Are there other things you want to do on the separate timetables?

Anyways, my solution (which could certainly be tightened up but is at least clear):

>> tt = timetable(rand(15,1),[1;1;1;0;0;1;1;1;1;0;1;1;1;1;1], ...
    'RowTimes',datetime(2019,6,19,0,0,0:14), ...
    'VariableNames',{'X' 'OnOff'});
>> tt.Group = 1 + [0; cumsum(diff([tt.OnOff])~=0)]
tt =
  15×3 timetable
            Time               X        OnOff    Group
    ____________________    ________    _____    _____
    19-Jun-2019 00:00:00     0.69989      1        1  
    19-Jun-2019 00:00:01     0.63853      1        1  
    19-Jun-2019 00:00:02    0.033604      1        1  
    19-Jun-2019 00:00:03    0.068806      0        2  
    19-Jun-2019 00:00:04      0.3196      0        2  
    19-Jun-2019 00:00:05     0.53086      1        3  
    19-Jun-2019 00:00:06     0.65445      1        3  
    19-Jun-2019 00:00:07     0.40762      1        3  
    19-Jun-2019 00:00:08     0.81998      1        3  
    19-Jun-2019 00:00:09     0.71836      0        4  
    19-Jun-2019 00:00:10     0.96865      1        5  
    19-Jun-2019 00:00:11     0.53133      1        5  
    19-Jun-2019 00:00:12     0.32515      1        5  
    19-Jun-2019 00:00:13     0.10563      1        5  
    19-Jun-2019 00:00:14     0.61096      1        5  
>> c = cell(numel(unique(tt.Group)),1);
>> for i = 1:length(c), c{i} = tt(tt.Group == i,1:2); end
>> c{:}
ans =
  3×2 timetable
            Time               X        OnOff
    ____________________    ________    _____
    19-Jun-2019 00:00:00     0.69989      1  
    19-Jun-2019 00:00:01     0.63853      1  
    19-Jun-2019 00:00:02    0.033604      1  
ans =
  2×2 timetable
            Time               X        OnOff
    ____________________    ________    _____
    19-Jun-2019 00:00:03    0.068806      0  
    19-Jun-2019 00:00:04      0.3196      0  
ans =
  4×2 timetable
            Time               X       OnOff
    ____________________    _______    _____
    19-Jun-2019 00:00:05    0.53086      1  
    19-Jun-2019 00:00:06    0.65445      1  
    19-Jun-2019 00:00:07    0.40762      1  
    19-Jun-2019 00:00:08    0.81998      1  
ans =
  1×2 timetable
            Time               X       OnOff
    ____________________    _______    _____
    19-Jun-2019 00:00:09    0.71836      0  
ans =
  5×2 timetable
            Time               X       OnOff
    ____________________    _______    _____
    19-Jun-2019 00:00:10    0.96865      1  
    19-Jun-2019 00:00:11    0.53133      1  
    19-Jun-2019 00:00:12    0.32515      1  
    19-Jun-2019 00:00:13    0.10563      1  
    19-Jun-2019 00:00:14    0.61096      1

Best Answer

Related Solutions

MATLAB: How to convert timestamps to number of seconds

MATLAB: Devide a table in several tables by criteria

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