How to make datenum more efficient for large arrays?

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Marian 2013-10-29

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评论： Cedric 2013-10-30

I am using textscan() to create an matrix that is 3,081,680 rows long. The very first column, A{1}, is the timestamp column, and it's elements look like this:

"2011-01-23 18:38:30"

I have tried using datenum() to convert this, but it is either taking too long or not working at all (longer than ten minutes). Is there a way I can make this more efficient?

Thanks!

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Cedric 2013-10-29

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编辑：Cedric 2013-10-29

What is the purpose ultimately? Do you need an accurate time stamp which accounts for the date and time? If you were computing daily averages for 2011 only, for example, we could find a way to generate month/day IDs probably faster than DATENUM.

Otherwise, there are FEX contributions, e.g. this one by Jan Simon: http://www.mathworks.com/matlabcentral/fileexchange/28093-datestr2num

as well as a few relevant threads, among which: http://undocumentedmatlab.com/blog/datenum-performance/

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Marian 2013-10-30

Ah, datevec! I have been teaching myself MATLAB and did not know of this function, but I believe that I needed datevec to read arrays, as datenum or datestr2num would not work for type "cell". Thanks so much!