How to change values in a vector

Im trying to reformat a time vector to only use the seconds. For example the data was recorded using the actual time in 20 second intervals: 11:06:30 11:06:50 11:07:10 the only thing that is relevant to me are the seconds. How do I adjust this without having to do it manually?

[Tim Fensterer]

i was thinking about trying to use the erase function to delete the substrings but i wasn't sure how to manage the fact that the "minutes" are changing

[KL]

How do you store these values?

[Tim Fensterer]

they are stored as a column vector "Sample Time

" 11:06:10 11:06:30 11:06:50 11:07:10 11:07:30 11:07:50 11:08:10 11:08:30 11:08:50 11:09:10 11:09:30 11:09:50 11:10:10 11:10:30 11:10:50 11:11:10 11:11:30 11:11:50 11:12:10 11:12:30 11:12:50 11:13:10 11:13:30 11:13:50 11:14:10 11:14:30 11:14:50 11:15:10 11:15:30 11:15:50 11:16:10 11:16:30 11:16:50 11:17:10 11:17:30 11:17:50 11:18:10 11:18:30 11:18:50 11:19:10 11:19:30 11:19:50 11:20:10 11:20:30 11:20:50 11:21:10 11:21:30 11:21:50 11:22:10 11:22:30 11:22:50 11:23:10 11:23:30 11:23:50 11:24:10 11:24:30 11:24:50 11:25:10 11:25:30 11:25:50 11:26:10 11:26:30 11:26:50 11:27:10 11:27:30 11:27:50 11:28:10 11:28:30 11:28:50 11:29:10 11:29:30 11:29:50 11:30:10 11:30:52 11:31:12 11:31:32 11:31:52 11:32:12 11:32:32 11:32:52 11:33:12 11:33:32 11:33:52 11:34:12 11:34:32 11:34:52 11:35:12 11:35:32 11:35:52 11:36:12 11:36:32 11:36:52 11:37:12 11:37:32 11:37:52 11:38:12 11:38:32 11:38:52 11:39:12 11:39:32 11:39:52 11:40:12 11:40:32 11:40:52 11:41:12 11:41:32 11:41:52 11:42:12 11:42:32 11:42:52 11:43:12 11:43:32 11:43:52 11:44:12 11:44:32 11:44:52 11:45:12 11:45:32 11:45:52 11:46:12 11:46:32 11:46:52 11:47:12

[Tim Fensterer]

not sure if this answers your question, I'm relatively new to Matlab / coding in general. I imported the data from an excel file generated by the lab equipment's software package.

[Tim Fensterer]

Also, if you look at the data above, you can see at 11:30:10 it jumps to 11:30:52, then continues on in 20 second intervals. this is because we stopped the system and then turned it back on

[berenice va-t-on]

clear X for i=1:size(Crop,3), X(:,i)=reshape(Crop(:,:,i),[10000 1]); end

averageFace=mean(X')';

A=double(X)-repmat(averageFace,[1 size(Crop,3)]);

[U,S,D]=svds(A, 30);

lTFaces=(U(:,1:20)')*(double(X)-repmat(averageFace,[1 size(Crop,3)])); UnknownFace=imread('47-1.JPG.jpg'); imagesc(UnknownFace) UnknownCrop=extract_face(rgb2gray(UnknownFace),100); close lUnknownFace=(U(:,1:20)')*(double(reshape(UnknownCrop,[10000 1]))-averageFace); EuclideanDist=sqrt(sum((lTFaces-repmat(lUnknownFace,[1 size(lTFaces,2)])).^2)); [match_score, match]=min(EuclideanDist) imagesc(reshape(X(:,match),[100 100])); colormap(gray); axis image

filenames=dir; for i=3:48, files{i-2}=filenames(i).name; dates{i-2}=filenames(i).date; end [ignore,idx]=sort(dates); sortedfiles=files(idx);

Answer 1

[KL]

One idea is to store them as datetime and then extract just seonds field, for example

dt = datetime('11:06:20');
secOnly = dt.Second

This should only give you the 20. You could do this for your whole range to store as a vector.

[Tim Fensterer]

Ok sounds good, How would i go about applying that to the entire vector? would i say something like (assuming the data above has the variable name 'sampletimefin') dt = datetime('sampletimefin') seconly = dt.Second

[KL]

The data you import from your excel file should be the input vector in this case. Suppose your vector, after importing, looks like this,

sampletimefin = ['11:06:10'; '11:06:30';'11:06:50'] %these are dummy data just to show you how it should look like
dt = datetime(sampletimefin)
secVec = dt.Second

[Tim Fensterer]

Awesome, that worked. thanks KL! If I were to decide to include the minutes as well, is the there a "dt." function for that too? I really appreciate your advice.

[KL]

Yes, just

dt.Minute

and so on. You can read more on this below link https://de.mathworks.com/help/matlab/ref/datetime.html#d119e193213 .

Answer 2

[Andrei Bobrov]

c = readtable('20171015.txt','delimiter',':','ReadVariableNames',false)
t = duration(c{:,:})
out = seconds(t);