MATLAB: Subsetting dates in a matrix

Question

Hello,

I have a time series in a matrix and first column is serial date numbers (up to millisecond precision), and other columns my samples. I would like to get those rows that belong to for example '12-Oct-2012'. I couldn't figure out how to write the logical operator to get a slice of this matrix. I would like to hopefully avoid some sort of slow string comparison.

Thanks in advance

Answer 1

You already have serialized/numeric time stamps in you array, so just convert date boundaries to numeric, and compare numbers: assuming your array is named data..

 lb_incl = datenum( '12-Oct-2012', 'dd-mmm-yyyy' ) ;
 ub_excl = datenum( '13-Oct-2012', 'dd-mmm-yyyy' ) ;
 id = data(:,1) >= lb_incl & data(:,1) < ub_excl ;
 dailyMean = mean( data(id,2) ) ;

or

 dailySlice = data(id,2:end) ;