Time and GPS data processing

Hello! I have a txt file with time data and coordinates. The time is recorded as hours-minutes-seconds without spaces. I need to select the coordinates at a certain point in time, for example: starting from 010400 30 seconds, following from 011000 30 seconds, and so on. By what means can this be done to set the necessary time intervals and the number of seconds of duration?

Answer 1

[Simon Chan]

You may edit the following three variables if you would like to set interval and duration.

initialtime = The first reporting time (example below: start from 01:26:00)

deltatime = Reporting interval (example below: every 6 minutes)

recordtime = Number of seconds you want to report for each interval. (example below: 30 seconds)

Of course, this cannot be greater than 'deltatime'

T = readtable('resultcopy.txt','Format','%{hhmmss}D %f %f');
initialtime = duration(01,26,00);
deltatime = duration(00,06,00);
recordtime = duration(00,00,30);
starttime = initialtime:deltatime:timeofday(T.Var1(end));
reporttime = [];
for k=1:length(starttime)
    temp = starttime(k):duration(00,00,01):starttime(k)+recordtime-duration(00,00,01);
    reporttime = [reporttime, temp];
end
idx = ismember(timeofday(T.Var1),reporttime);
result = table(T(idx,:));

[Jony Smith]

Thank you very much for the answer! Your solution helped in solving my problem!

Answer 2

[Chunru]

% Read data from file
T = readtable('resultcopy.txt');
% Convert to datetime format
T.Var1 = datetime(num2str(T.Var1, '%06d'), 'InputFormat', 'HHmmss');
% Select data by comparing datetime
idx = T.Var1 >= datetime('012600', 'InputFormat', 'HHmmss') & T.Var1 <= datetime('012630', 'InputFormat', 'HHmmss');
T(idx, :)

ans = 31×3 table
            Var1             Var2     Var3 
    ____________________    ______    _____

    20-Jul-2021 01:26:00    5103.2    15044
    20-Jul-2021 01:26:01    5103.2    15044
    20-Jul-2021 01:26:02    5103.2    15044
    20-Jul-2021 01:26:03    5103.2    15044
    20-Jul-2021 01:26:04    5103.2    15044
    20-Jul-2021 01:26:05    5103.2    15044
    20-Jul-2021 01:26:06    5103.2    15044
    20-Jul-2021 01:26:07    5103.3    15044
    20-Jul-2021 01:26:08    5103.3    15044
    20-Jul-2021 01:26:09    5103.3    15044
    20-Jul-2021 01:26:10    5103.3    15044
    20-Jul-2021 01:26:11    5103.3    15044
    20-Jul-2021 01:26:12    5103.3    15044
    20-Jul-2021 01:26:13    5103.3    15044
    20-Jul-2021 01:26:14    5103.3    15044
    20-Jul-2021 01:26:15    5103.3    15044

[Jony Smith]

Thank you! But, if I don't need to convert the time to the date and time format, but I need to leave it as it is, in a string variable.

[Chunru]

Then you can create a separate variable:

% Read data from file
T = readtable('resultcopy.txt');
% Convert to datetime format
t0 = datetime(num2str(T.Var1, '%06d'), 'InputFormat', 'HHmmss');
% Select data by comparing datetime
idx = t0 >= datetime('012600', 'InputFormat', 'HHmmss') & t0 <= datetime('012630', 'InputFormat', 'HHmmss');
T(idx, :)

ans = 31×3 table
    Var1      Var2     Var3 
    _____    ______    _____

    12600    5103.2    15044
    12601    5103.2    15044
    12602    5103.2    15044
    12603    5103.2    15044
    12604    5103.2    15044
    12605    5103.2    15044
    12606    5103.2    15044
    12607    5103.3    15044
    12608    5103.3    15044
    12609    5103.3    15044
    12610    5103.3    15044
    12611    5103.3    15044
    12612    5103.3    15044
    12613    5103.3    15044
    12614    5103.3    15044
    12615    5103.3    15044

[Peter Perkins]

"I don't need to convert the time to the date and time format, but I need to leave it as it is, in a string variable."

Jony, you likely don't want to do that. If you want to keep working with timestamps in that format, just set the format as Chunru more or less shows.

I'm not clear on what you need to do. "select the coordinates at a certain point in time, for example: starting from 010400 30 seconds" sounds contradictory--in any 30 sec window I assume you have multiple coordinates, so you need to say how you want to select.

You say, "for example: starting from 010400 30 seconds, following from 011000 30 seconds, and so on.", suggesting that you need to do this at many time points. My suggestion is to use a timetable, and use retime to aggregate 30 sec time bins. I can't really offer any example code, because I don't know specifically what you are trying to do.