How to make datenum more efficient for large arrays?
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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
il 29 Ott 2013
Modificato: Cedric
il 29 Ott 2013
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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Cedric
il 30 Ott 2013
You're welcome. Let me know if you go for an ACCUMARRAY approach for binning and need help with that.
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Kelly Kearney
il 29 Ott 2013
Are you specifying the date format? Particularly for large arrays,
datenum(A{1}, 'yyyy-mm-dd HH:MM:SS')
will be much faster than
datenum(A{1})
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