Return index of datetime column in a table

Hi!

I have a very long table which I want to return index to specific raws.

>> head(HData)

          Time             
    _____________________ 

    '2019.08.22 12:00:00'
    '2019.08.22 12:15:00'
    '2019.08.22 12:30:00'

I want to return in dex for the raws

    '2019.08.22 12:00:00'

Thanks.

[Ted Shultz]

is the time variable a matlab datetime number, or is it a string? This will use much less data, and be easier to work with if it was a datetime.

https://www.mathworks.com/help/matlab/ref/datetime.html

it usualy isn't too much work to convert strings to datetime arrays.

Answer 1

[Akira Agata]

If your HData.Time column is string:

% index of zero seconds
idx_s = cellfun(@(x) ~isempty(x),regexp(HData.Time,'00$','match'));

% index of zero minutes
idx_m = cellfun(@(x) ~isempty(x),regexp(HData.Time,':00:','match'));

Or, if your HData.Time column is datetime, it becomes much simpler, like:

% index of zero seconds
idx_s = HData.Time.Second == 0;

% index of zero minutes
idx_m = HData.Time.Minute == 0;