Writing a conditional statement for timeseries data

Hi,

In the code attached, I want to write a conditional statement based on datetime and sunrise sunset time. Sunrise is the sunrise time as character vector, sunrise_new is the sunrise time after converting it to HHMM format using datenum (but i am not sure which one to use). I want to figure out if it's a day or night based on datetime and sunrise sunset data. My code should read like:

If HH:MM value in DateTime is > sunrise & < sunset

time = 1

If HH:MM value in DateTime < sunrise & > sunset

time = 0

end

I don't know how to properly write conditional statement in matlab yet.

[Walter Roberson]

isbetween

Answer 1

[Rohit]

Hi,

In order to compare the times, you can use the "datenum()" function as shown in the below example:

% Getting current time
now=datetime('now')

now = datetime
   22-Aug-2022 08:48:58

% Converting datetime to serial date number
format long
hour=now.Hour;
minn=now.Minute;
time_to_check=datenum(hour+":"+minn,'HH:MM')

time_to_check = 
     7.385223666666667e+05

sunrise = datenum('07:36', 'HH:MM' );
sunset = datenum('17:46', 'HH:MM' ) ;

% Conditional statement to figure out if it's a day or night 
if time_to_check<sunrise || time_to_check>sunset
    time=0;
else
    time=1;
end

You can refer to the below Documentation link for "datenum" function along with the MATLAB Answers link:

Convert date and time to serial date number - MATLAB datenum

how to compare 2 different time in matlab

[Benju Baniya]

Thank you. When I use the conditional statment, I get an error saying "Operands to the logical and (&&) and or (||) operators must be convertible to logical scalar values".

I used this code: Here joined_eddy is the merged file of provided dataet.

format = long

hour = joined_eddy.DateTime.Hour

min = joined_eddy.DateTime.Minute

time_to_check = datenum(hour+":"+ min, 'HH:MM')

%Day and night values

if time_to_check<joined_eddy.Sunrise || time_to_check>joined_eddy.Sunset

time = 0;

else

time = 1;

end

[Walter Roberson]

No loop needed, no datenum() needed

time = isbetween(joined_eddy.DateTime, joined_eddy.Sunrise, joined_eddy.Sunset, 'closed');