hours(diff​(datetime(​[t1;t2]))) function

i have a 300 x 2 table, i want to calculate time differences and i want to count how many of them are more than 3 hours. [a, b] is the size of the table. it gives an error in the = c line & it says Unable to use a value of type duration as an index. how do i solve this?

below is the related part of the code. thank you so much

for n = 1:a

        t1 = y(n,1)
        t2 = y(n,2)
        hours(diff(datetime(t1;t2]))) = c
          
        
          if c > 3
           x = x+ 1
          end
  
end

[KSSV]

You are getting any error? What problem you are facing?

[Berk Opla]

yes i'm getting "Unable to use a value of type duration as an index." for the line of

hours(diff(datetime(t1;t2]))) = c

Answer 1

[Berk Opla]

figured it out

hours(diff(datetime(t1;t2]))) = c is wrong

it should be c = hours(diff(datetime([t1;t2])))

for some reason

[Star Strider]

That syntax is incorrect.

[Berk Opla]

yeah fixed it now. the problem was the place of the c

Answer 2

[dpb]

hours(diff(datetime(t1;t2]))) = c

You're using hours that is a builtin function as an array name on the LHS of an assignment statement and you also have an unmatched "]" bracket in the expression.

You also don't need a loop here...use MATLAB vectorized operations instead...

You don't provide what y variable contains; presuming it can be converted to a datetime, then if the answer is to determine how many of the time differences between the two columns are > 3 hours, then

nGt3=sum((datetime(y:,1)-datetime(y:,2))>3);

This presumes as your code that the first date is in the second column not the first -- one would normally think that would be the other way 'round; in which case would want to reverse the column indices in the difference calculation.

Answer 3

[Peter Perkins]

In addition to what others have said, you probably don't need the "hours" in

hours(diff(datetime(t1;t2])))

All that does is turn the duration that diff returns into a number. You are probably better off leaving it as duration, and replacing "3" with hours(3). More expressive.