Reading content of a file using readtable return NaT for Time

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Life is Wonderful 2019-8-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476858-reading-content-of-a-file-using-readtable-return-nat-for-time

编辑： Life is Wonderful 2019-9-5

采纳的回答： Walter Roberson

Please find the attached file. I want to use readtable to parse the file using readtable function.

I want Date and message content separatly done.

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Life is Wonderful 2019-8-20

eventlog.txt

Added file

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Answer 1

Walter Roberson 2019-9-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476858-reading-content-of-a-file-using-readtable-return-nat-for-time#answer_390464

编辑：Andrei Bobrov 2019-9-5

filename = 'eventlog.txt';
opt = detectImportOptions(filename);
opt = setvartype(opt, 5, 'char');
datatable = readtable(filename, opt);

datatable{:,2} is now the datetime entry, and datatable(:,[3 4 5]) are the fields.

As the fields are delimited, it is not completely clear whether you wanted everything to the end of the line as a single character vector complete with '|' inside, or if you wanted the fields broken out. The above breaks them out.

string(datatable{:,3}) + " | " + string(datatable{:,4}) + " | " + string(datatable{:,5})

would put the fields back together, except with an extra trailing " | " on the lines that had only 4 fields originally.

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Andrei Bobrov 2019-9-5

Maybe

opt = setvartype(opt, 4, 'char');

Andrei Bobrov 2019-9-5

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Answer 2

Andrei Bobrov 2019-9-5

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https://ww2.mathworks.cn/matlabcentral/answers/476858-reading-content-of-a-file-using-readtable-return-nat-for-time#answer_390465

编辑：Andrei Bobrov 2019-9-5

T = readtable('eventlog.txt','format',...
    '%d %{yyyy-MM-dd HH:mm:SS}D %s %s %s','delimiter','|',...
                                  'ReadVariableNames',false);

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Life is Wonderful 2019-9-5

编辑：Life is Wonderful 2019-9-5

Thanks a lot . I will test the implementation.

I have a question if same format file is passed multiple times

say filename1,filename2,filename3, & so on

then I would like to know

how can I make a function out it ,if sugested piece of code is called multiple times for different files?
how to pass the index to Output of readtable "datatable " ?

"datatable = readtable(filename, opt); "

or

"T = readtable('eventlog.txt','format',...
    '%d %{yyyy-MM-dd HH:mm:SS}D %s %s %s','delimiter','|',...
                                  'ReadVariableNames',false);"

T{idx} ?

Content = T{idx}; ???

or

Content = datatable{idx};

how to pass the argument for next routine & what modification is recommended in below code

I would be using below code with the output of readtable

function [joinedtimetable] = get_fieldnames(Content)
[contentfields] = fieldnames(Content);
for fieldidx = 1:numel(contentfields)    %iterate over each field of Content
    structtable = struct2cell(Content.(contentfields{fieldidx}));  %extract the structure within the field by converting it to cell array (avoids having to work out what its name is)
    structtable = structtable{1}; %get the table out of the cell
    structtable.Date = duration(structtable.Date.Hour, structtable.Date.Minute, structtable.Date.Second);  %extract h/m/s and make that a duration.
    structtable.Date = structtable.Date - structtable.Date(1);  %elapsed time since start of log.
    structtable.Properties.VariableNames{1} = 'WeirdDuration';  %rename the time column {system time logs are wired}
    structtimetable = table2timetable(structtable(:, {'WeirdDuration','Message'}));  %convert to timetable, only keeping Date and Message
    structtimetable.Properties.VariableNames{1} = sprintf('Message_%s', contentfields{fieldidx});  %rename Message variable so we know where it came from
    structtimetable = rmmissing(structtimetable);  %remove invalid rows to avoid problems with synchronize
    structtimetable.Properties.RowTimes.Format = 'hh:mm:ss.SSS'; %duration format to support millisecond
    if fieldidx == 1
        joinedtimetable = structtimetable;  %1st time, create output
    else 
        fieldidx
        joinedtimetable = synchronize(joinedtimetable, structtimetable, 'union'); %subsequent times, synchronize. Choose whichever method is prefered
    end
end