How to make 2 data sets the same size

Hello,

I have two data sets (Temperature over Time and Absorption over Time) over the same time interval. The problem is that one set has 6000 values(~10 per second) and the other one 900(~1.5 per second). I would like to cut down both sets to the same size, by taking the average value for each second, but I am not sure how to do this. The function I am writing is getting rather convoluted and confusing with several nested loops, so I am wondering if there is some easy way to do this that I am overlooking.

Thanks in advance for any help, Angela

[Angela]

Thanks, both ways work fine.

Answer 1

[Kevin Claytor]

Have a look at the resample function;

>> help resample
 resample  Change the sampling rate of a signal.
    Y = resample(X,P,Q) resamples the sequence in vector X at P/Q times
    the original sample rate using a polyphase implementation.  Y is P/Q 
    times the length of X (or the ceiling of this if P/Q is not an integer).  
    P and Q must be positive integers.

For example you would be looking at;

time_a = linspace(1,10,900);
time_t = linspace(1,10,6000);
temp = rand(size(time_t))
absorb = rand(size(time_a));
temp_undersampled = resample(temp, length(absorb), length(temp));
size(temp_undersampled)

This is a pretty rough example, and if you want to go the other way, there's interp1 (that's a 1 not an ell) - but the usual caveats apply with interpolation.

Answer 2

[Andrei Bobrov]

x1 = randi(500,6000,1); % your data
x2 = randi(600,900,1);  %

Fx1 = griddedInterpolant(x1);
Fx2 = griddedInterpolant(x2);

out = [Fx1(linspace(1,numel(x1),600)'), Fx2(linspace(1,numel(x2),600)')];

[Madina Makhmutova]

Dear Andrei,

How can I adjust this code without using for loops if instead of being a vector x1 is a matrix?

x1 = randi(500,6000,5);

Thank you.