if loop to find values in a variable

I have 2 arrays of numbers, t and Q. I want to use an if loop to do the following:

• find if tfind is present in the variable t.
• if this number is present, find the index of the number within this array.
• find the number in the variable Q which corresponds to this index

my code runs, but the variable c is empty. Can anybody help?

t = [4 5 7 8 10 11 12 15 17 20 22 24 26 27 28];
Q = [1 3 4 1 5 8 4 2 6 1 4 2 8 3 5];

p = 10;
np = 3;

for i = 1:p
c = [];
for j = 1:np
    tfind = (j-1)*p+i
    if ismember(t, tfind) %find if tfind is in t
        loc = find(t=tfind) % find the index of tfind within t
        q = Q(loc) %find the number in Q which corresponds to this index
    end
    c = [c;q] %assign the values of q to new variable
end
end 

Answer 1

[Matt J]

One possibility

t = [4 5 7 8 10 11 12 15 17 20 22 24 26 27 28];
Q = [1 3 4 1 5 8 4 2 6 1 4 2 8 3 5];

p = 10;
np = 3;

c = cell(1,p*np); k=0;
for i = 1:p
 for j = 1:np
     
    tfind = (j-1)*p+i;

    k=k+1;
    c{k}=Q(t==tfind);
    
 end
end 

c=cell2mat(c)

c = 1×15

8 4 4 1 2 3 2 8 4 6 3 1 5 5 1

[C.G.]

Thank you for your response.

Your answer didnt quite answer my question but got me closer to it.

What I want it to do, is to loop through and save each iteration of c_s rather than just the last one. I want to end up with 3 rows of data that I can take a mean from. Do you know how I can do this?

t = [4 5 7 8 10 11 12 15 17 20 22 24 26 27 28];
Q = [1 3 4 1 5 8 4 2 6 1 4 2 8 3 5];
p = 10;
Lti = 30;
np = Lti/p;
c = []; %ensemble average signal

for i = 1:p
            c_s = []; %sediment flux values equal to each second of the period
    for j = 1:np 
            tfind = (j-1)*p+i; 
            c_s = Q(t==tfind);
    end
    c = [c;mean(c_s)];
end 
c

c = 10×1

NaN 4 NaN 2 NaN 8 3 5 NaN NaN

[Matt J]

I want to end up with 3 rows of data that I can take a mean from.

So, c is meant to have np=3 rows? How many columns?

Maybe this is what you mean:

t = [4 5 7 8 10 11 12 15 17 20 22 24 26 27 28];
Q = [1 3 4 1 5 8 4 2 6 1 4 2 8 3 5];
p = 10;
Lti = 30;
np = Lti/p;
c = nan(np,1); %ensemble average signal

for j = 1:np 
  for i = 1:p


            tfind = (j-1)*p+i; 
            c(j) = mean( Q(t==tfind) );

  end 
end

  c %three rows

c = 3×1

5 1 NaN