The loop is continuously running

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MA 2021-10-17

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https://ww2.mathworks.cn/matlabcentral/answers/1565531-the-loop-is-continuously-running

评论： Scott MacKenzie 2021-10-17

I am trying to compare the date values for two tables named T and S, if any matching of the dates is found we should copy the value of the variable 'solar' from S and add it to its corresponding date in T. I implemented that using the following for loop, but the loop keep continuously running for some reason. and we are not getting our desired result.

having that T is 37028x5 table and S is 25550x2 table.

how can we fix that or would there be a better way to do this rather than a for loop?

for jj=1:size(T)
    for ii=1:size(S)
if (year(T.Date(jj))==year(S.date(ii))  & month(T.Date(jj))==month(S.date(ii))  & day(T.Date(jj))==day(S.date(ii))   )
    T.solarT(jj)=S.solar(ii);
end 
     end 
end

attached are parts of the tables S and T respectively,

thanks for giving it a look,

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Answer 1

Scott MacKenzie 2021-10-17

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Your loop is fine, but is inefficient and takes a long time to execute. Instead of the loop, try this:

[Lia, Locb] = ismember(T.Date, S.date);
idx = Locb(Locb > 0);
T.solarT(Lia) = S.solar(idx);

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MA 2021-10-17

Thank you for the help!. really appreciate it.

Scott MacKenzie 2021-10-17

You're welcome. Glad to help.

Another approach to consider is converting the tables (which include datetime columns) to timetables and then using the synchronize function. Check the timetable documentation for examples.

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