Deleting rows in a matrix with condition on its column value

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itzhak mal 2018-9-26

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评论： itzhak mal 2018-9-26

采纳的回答： James Tursa

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Hi there,

I have a text file with about 14 millions rows and 11 columns. On the 11th column, there are values that are really small.. and I want to get rid of the rows that their 11th column has a value that is smaller than 10^-(12).

I loaded the file into matlab and now it's stored in a variable as a matrix with 14 million rows and 11 columns.. and I wrote this code but it is so painfully slow that it takes it about 1 second per row.. so that's 150 days for the whole matrix.

that's my slow code:

for i = 1 : 13847014

    if New_LongDataUn(i,11) < 10^-(12) 
         New_LongDataUn(i,:) = [];
    end
end

Thanks for all the kind help you guys!

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采纳的回答

James Tursa 2018-9-26

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https://ww2.mathworks.cn/matlabcentral/answers/420760-deleting-rows-in-a-matrix-with-condition-on-its-column-value#answer_338422

编辑：James Tursa 2018-9-26

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New_LongDataUn(New_LongDataUn(:,11) < 1e-12,:) = [];

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James Tursa 2018-9-26

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If you mean into a mat file, then simply

save your_matfile_name New_LongDataUn

itzhak mal 2018-9-26

thanks again! so so much!

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