Exporting value to .csv file with updated value from a timer

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P 2013-12-12

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https://ww2.mathworks.cn/matlabcentral/answers/109485-exporting-value-to-csv-file-with-updated-value-from-a-timer

评论： per isakson 2013-12-12

I have a timer which updates a value in my script every minute

Period = 60; % Update period in seconds
tim = timer('Period', Period, 'ExecutionMode', 'fixedRate',...
    'TimerFcn', 'MyScript');
start(tim)
stop(tim)

I want to store the updated value in the next row (same column) of a .csv file every time the timer resets

%Writes the current value to 60 mins.csv in row 1, column 1
csvwrite('60 mins.csv',MyValue,0,0);

My guess is that i need a counter to increase the row number with each updated value/timer iteration. I want to collect at least 1440 values (a full day).

Any thoughts?

Note: the timer IS supposed to leave the whole script on an infinite loop, just in case anybody was wondering.

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Answer 1

per isakson 2013-12-12

1
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https://ww2.mathworks.cn/matlabcentral/answers/109485-exporting-value-to-csv-file-with-updated-value-from-a-timer#answer_118130

编辑：per isakson 2013-12-12

在 MATLAB Online 中打开

A couple of thoughts:

see Running Script using Timer and note the comment by Alfonso Nieto-Castanon
an alternative to cswrite is fopen( ..., 'a') together with fprintf. No need for a counter; it appends to the end of the file. Or maybe dlmwrite(filename, M, '-append')

Appended:

Try

   %%my_timer_test
        tmr = timer                             ...
            (   'Name'          , 'my_timer'    ...
            ,   'TimerFcn'      , @my_fcn       ...
            ,   'BusyMode'      , 'drop'        ...
            ,   'ExecutionMode' , 'fixedRate'   ...
            ,   'Period'        ,  6            ...
            ,   'StartDelay'    ,  1            ...
            ); 
        start( tmr )

where

    function    my_fcn( tmr, data )
        filespec1  = 'my_fprintf_values.csv';
        filespec2  = 'my_dlmwrite_values.csv';
        new_value  = randn(1); % stand-in for urlread( something ) 
        fid = fopen( filespec1, 'a' );
        fprintf( fid, '%f,%f\n', now, new_value );
        fclose( fid );
        M = [ now, new_value ];  % default precision not sufficient for now
        dlmwrite( filespec2, M, '-append' )
    end

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P 2013-12-12

MyValue is determined by my script. The script downloads a csv file from a URL every time the script is run. The URL data is just a single value in a csv file which causes MyValue to change. The timer just re-runs the whole script every minute so that the URL data is downloaded again and a new MyValue is calculated from the new URL data. I want to append my own CSV file so that I can store the minutely changing MyValues.

The URL data is updated minutely from an external source and is basically a single cell value in a csv file.