Find specific date/time from a series of datenums
19 views (last 30 days)
Show older comments
I have a 7184x72001 double matrix where the first column is a list of serial datenumbers.
I am happy to keep the format this way, but I need to be able to select a specific date/time from this list so that I can extract the data from certain days/times that I am interested in.
So, is it either possible to:
-search from a list of datenums to find a specific date/time that I provide?
-add a column of str data to a matrix of double?
or-convert all of the datenums to date and time?
I have tried the second approach so far:
D=csvread('Tiritiri5280_PSD_1sHammingWindow_50%Overlap_output.csv'); %load in data
t=D(:,1); %extract time column
formatOut='yymmddHHMMSS';
times=datestr(t, formatOut); %convert t column datenums to date and time
rows=(1:length(times)).'; %number of dates and times we have
D_new=[rows D]; %add new column to D
D_new(:,1)=timeslist(:,2); %add times in different format to D
-this works but I now get the datenum in a different format which is also not readable. How do I keep the date time in yymmddhhmmss in a double matrix? Is this possible?
Here,column 1 is the new dates/times that I tried to insert in readable form, and column 2 is serial datenum.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/238567/image.png)
2 Comments
Nicolas B.
on 17 Sep 2019
Hi,
in a matrix, you have the problem that you can only have 1 data type for all your data. Maybe a cell array could help you?
Accepted Answer
Steven Lord
on 17 Sep 2019
If you're going to be doing a lot of processing of this data based on the times, consider turning your column of date numbers into a datetime array and using that datetime array to convert your data matrix into a timetable. Once you do this you could extract data from the timetable based on the times for each row using a timerange as shown in the "Subscript on Time Range" section on this documentation page. You could also resample or aggregate your timetable data using a certain time basis, as shown here.
1 Comment
More Answers (1)
Ted Shultz
on 17 Sep 2019
It looks like the start of your approach is reasonable. Once you make a “times” array, there is no need to add it back to the “D” matrix. You can use that as your index.
For example:
indexOfInterest = (times > t_one) && (times < t_two);
someData =d(indexOfInterest, :);
See Also
Categories
Find more on Dates and Time in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!