How to extract Datetime string to separate columns of yyyy dd mm hh mm

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Dennis
Dennis 2023-1-9
评论： Siddharth Bhutiya 2023-1-26
Am a noob, so bear with me, I need to extract the date string and separate the year day month hour and minute to separate column within the dataframe. AM getting an error with ectractBetween. What could I be doing wrong? Ive started with just the year in this code
ararat = importdata("ararat.txt");
Q1 = [ararat(:,1)];
resQ1 = num2str(Q1)
for N=1:length(resQ1)
year = extractBetween(resQ1, 1,4)
end

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采纳的回答

Stephen23
Stephen23 2023-1-9
编辑：Stephen23 2023-1-9
Ran in:
That is a very unfortunate date format. Best avoided.
T = readtable('ararat.txt', 'Format','%{yyyyddMMHHmm}D%f'); % ugh.
T.Properties.VariableNames = {'DT','Val'};
T.DT.Format = 'yyyy-MM-dd HH:mm:ss'; % aaah, much better :)
[T.Year,T.Month,T.Day] = ymd(T.DT);
[T.Hour,T.Minute,T.Second] = hms(T.DT);
display(T)
T = 52560×8 table
DT Val Year Month Day Hour Minute Second ___________________ ______ ____ _____ ___ ____ ______ ______ 2020-03-21 12:00:00 3.9798 2020 3 21 12 0 0 2020-03-21 12:10:00 4.3032 2020 3 21 12 10 0 2020-03-21 12:20:00 4.2702 2020 3 21 12 20 0 2020-03-21 12:30:00 4.0128 2020 3 21 12 30 0 2020-03-21 12:40:00 4.9302 2020 3 21 12 40 0 2020-03-21 12:50:00 5.445 2020 3 21 12 50 0 2020-03-21 13:00:00 4.983 2020 3 21 13 0 0 2020-03-21 13:10:00 3.8544 2020 3 21 13 10 0 2020-03-21 13:20:00 7.2072 2020 3 21 13 20 0 2020-03-21 13:30:00 7.557 2020 3 21 13 30 0 2020-03-21 13:40:00 7.6098 2020 3 21 13 40 0 2020-03-21 13:50:00 7.0686 2020 3 21 13 50 0 2020-03-21 14:00:00 6.666 2020 3 21 14 0 0 2020-03-21 14:10:00 6.0588 2020 3 21 14 10 0 2020-03-21 14:20:00 5.8674 2020 3 21 14 20 0 2020-03-21 14:30:00 5.7156 2020 3 21 14 30 0
  2 个评论
Siddharth Bhutiya
Siddharth Bhutiya 2023-1-26
You dont even need to call ymd or hms here. For example if DT is a datetime then doing DT.Year would give you the year of all datetime, DT.Month, the month and so on. So this could be done like this.
T.Year = T.DT.Year;
T.Month = T.DT.Month; % and so on

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更多回答（1 个）

Mohammad Sami
Mohammad Sami 2023-1-9
Ran in:
varNames = {'dt','val'} ;
varTypes = {'datetime','double'} ;
delimiter = '\t';
opts = delimitedTextImportOptions('VariableNames',varNames,...
'VariableTypes',varTypes,...
'Delimiter',delimiter);
% specify the datetime input format to read the column as datetime value
opts = setvaropts(opts,{'dt'},'InputFormat','yyyyddMMHHmm');
a = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1256912/ararat.txt',opts);
head(a);
dt val ____________ ______ 202021031200 3.9798 202021031210 4.3032 202021031220 4.2702 202021031230 4.0128 202021031240 4.9302 202021031250 5.445 202021031300 4.983 202021031310 3.8544
% use datevec function to extract year, month, date, hour and minute values
[a.y,a.M,a.d,a.H,a.m] = datevec(a.dt);
head(a);
dt val y M d H m ____________ ______ ____ _ __ __ __ 202021031200 3.9798 2020 3 21 12 0 202021031210 4.3032 2020 3 21 12 10 202021031220 4.2702 2020 3 21 12 20 202021031230 4.0128 2020 3 21 12 30 202021031240 4.9302 2020 3 21 12 40 202021031250 5.445 2020 3 21 12 50 202021031300 4.983 2020 3 21 13 0 202021031310 3.8544 2020 3 21 13 10

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