I have a time series which my sensors recorded them in this format: 10.02.42.415 instead of this: 10:02:42.415 ! How can I fix my entire array (which is 465637 samples!)??

One of my sensors had an error during my data collection apparently and recorded the time series in a wrong format. I need to convert 10.02.42.415 to this: 10:02:42.415 in order to sync this time series with my other sensors. Thank you for your help

Answer 1

[Cris LaPierre]

The simplest way I can think of is to use datetime. Since you have no date associated with the time, sutract off today's date to leave time.

T = '10.02.42.415';
newT = datetime(T,'InputFormat','hh.mm.ss.SSS') - datetime('today');
newT.Format = 'hh:mm:ss.SSS'

newT = duration
   10:02:42.415

[Khashayarash Abas]

Hi @Cris LaPierre,

Thank you this worked well but there is a new problem. Could you please read my comments down bellow?

Regards,

Kash

[Cris LaPierre]

It looks like you left some details out of your original post that make a difference. For example, you do have dates associated with your time.

My recommendation is to not use datenum. There are newer, better ways to represent dates and times in MATLAB. I would suggest using datetimes and durations for your first 3 columns, and a table to store it. It's a little more upfront work to get the import formatted correctly, but can be much easier to work with and avoid mistakes.

participant = "p1";
% there was no left wrist file, but there was a right
file_name= strcat(participant, '_right_wrist_accel.txt');
% set import settings
opts = detectImportOptions(file_name);
opts.VariableNames = ["epoch","timestamp","elapsed","X","Y","Z"];
opts = setvartype(opts,2,"datetime");
% Note that timezone is hardcoded. Your 2 files have different timezones
% If you do not need timezone, you can remove it
opts = setvaropts(opts,2,'InputFormat','yyyy-dd-MM''T''hh.mm.ss.SSS','TimeZone','-0500');
data = readtable(file_name,opts);

% convert epoch and elapsed to durations so that units can be tracked
data.epoch = milliseconds(data.epoch);
data.elapsed = seconds(data.elapsed);
data.timestamp.Format = "yyyy-dd-MM HH:mm:ss.SSS"

Your _lol_ file contains a different separator for time. Update the InputFormat to match (uses colons instead of periods).

Answer 2

[Khashayarash Abas]

I have 8 different sensor. To sync my trials I used this code for all other sensors and they worked well:

participant = "p1";
file_name= strcat(participant, '_left_wrist_accel.txt');
fid = fopen(file_name,'r');
D = textscan(fid,'%f %s %f %f %f %f','HeaderLines',1);
fclose(fid);
data_time_D = D{1,2};
data_time_D = extractAfter(data_time_D, "T");
data_time_D = cellfun(@(S) S(1:end-1), data_time_D, 'Uniform', 0);
data_time_number_D = datenum(data_time_D); 
%Now that I used your function:
DD = datetime(data_time_D,'InputFormat','hh.mm.ss.SSS') - datetime('today');
DD.Format = 'hh:mm:ss.SSS'
% now if I use the data_time_number_D it will give me a different numbers which I guess it's because my array is duration 
%format not cell. How can I get the same format for data_time_number_D as before?
%data_time_number_D for Other sensors (e.g., lol acceleration) was like:
%  7.381575358067129e+05
%but for your suggested function it was like:
%  0.440958333333333

[John D'Errico]

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