How to find values for corresponding elements

Hello

I have a code that when applied to hourly discharge data, it gives the possition of peaks in the data serries. now i want to optain a peak time serries in a vector that has the same length of discharge but only have the peak discharges and the rest are NaN. can anyone help please?? i have included an example to clarify what i need

time(hr) Q given output(hr) wanted output

1 1 3 NaN

2 3 7 NaN

3 5 5

4 3 NaN

5 1 NaN

6 2 NaN

7 6 6

8 2 NaN

9 1 NaN

Answer 1

[Walter Roberson]

wanted_output = nan(length(time_vector),1);
mask = islocalmax(Q);
wanted_output(mask) = Q(mask);

[Hazhan Majeed]

many thanks.

i also wanted to shange the length of given-output vector to be the same as length of Q. any idea how i can do that. thanks

[Walter Roberson]

given_output(end+1:length(time_vector)) = nan;