using if to find a value in one variable, but then give you the value of a second variable

Hi all,

Ok so I have river runoff data for around 100 days, and I would lke to find the time of maximum runoff on each day. I reshaped the data (Q) into an x,y matrix (hours,days), but so far have had no luck getting the code to work. I tried it first with made up data and the code below worked fine:

for x=1:24;

for y=1:4;

if Q(x,:)==max(y)

Peak=T(x,:);

end

end

end

The variable T is matrix of the time with 1:24 repeated for each day. Peak is the variable of time of maximum runoff.Trouble is I can't get this to work with my real data, I have already taken out the NaNs and replaced them with 1. There is no error it just runs through without making Peak. I found the maximum for each day sepeately and it works fine for days without NaNs. Any ideas??

I would be greatful for any suggestions, Thanks, Cat

Answer 1

[Oleg Komarov]

[val,idx] = max(Q)

This is the row-wise maximum, i.e. along the rows for each column. idx says on which row the max is found. Since each day is a different column, the idx tells you which hour.

[Catriona]

Thanks, that's a much more concise way of doing it...I haven't learnt these clever Matlab ways yet!!