Creating histogram from a datetime vector

Hello guys!

I was trying to plot a datetime arrangement (vector) in a 12-hour histogram.

The problem is that when I try to plot it, it considers the whole date (since each element has a dd-MM-yy HH:mm:ss format), so I was wondering if is possible to isolate the hour in order to get an histogram that shows the hourly frecuency in a single day (only considering the hour). Another option I was considering is transforming the HH element into another data type easier to plot, but once again, I am not sure how to do it.

Thank you in advance,

Carlos.

Answer 1

[Star Strider]

I am not certain what your data are or the actual result you want.

Try this:

DT  = datetime('now')+hours(0:72).';                            % Create ‘datetime’ Array
T1 = table(DT, rand(size(DT)));                                 % Create Table With Data
[UCol1,~,ix] = unique(mod(hour(T1{:,1}),12));                   % Unique Values & Indices

Tally = accumarray(ix, T1{:,2});                                % Counts

figure
bar(UCol1, Tally)
grid

.

[Carlos Armas]

Thank you! it completely solved my problem.

[Star Strider]

As always, my pleasure!

Answer 2

[Steven Lord]

rightNow = datetime('now')

rightNow = datetime
   30-Dec-2020 19:10:28

howLongSinceMidnight = timeofday(rightNow)

howLongSinceMidnight = duration
   19:10:28