Writing a huge table to a text file is taking a very long time (R2013b)

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Alessandro Zaupa 2014-2-19

2
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回答： Chad Greene 2014-7-21

Hallo everyone, I have a table of 1,400,000 rows and 13 columns. 3 columns have integer data, 1 has string data and the others have double data. calculations on table columns are quick, but it takes 18 minutes (!) writing it to a text file with the "writetable" function (using a tab as delimiter).

I tried to use a loop with fprintf'ing each row, but I got an error message: fprintf doesn't work with tables.

Is there a way to speed up things in writing?

Thanks in advance.

Alessandro

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Ivan 2014-7-21

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I am struggling with the same problem. Here is sample code to illustrate it:

test = (1:1000000)';
testT = table(test);
fprintf(1, 'time: %s\n', datestr(now));
writetable(testT, 'C:\TEMP\testT.csv');
fprintf(1, 'time: %s\n', datestr(now));
save('C:\TEMP\testT.mat', 'testT');
fprintf(1, 'time: %s\n', datestr(now));

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Answer 1

Chad Greene 2014-7-21

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I've used dlmwrite for comma-delimited text files about this size, but I had trouble mixing numbers and strings. Using only numeric data, a single column of a million data points took about a minute to write. Can you write multiple text files--break it up by column or rows?