Filling in multidimensional array efficiently

I need to fill in array of the size (900,1800,80,60) --> (tr,t,f,ch) through a for loop. In every iteration, I will get a bunch of data for a particular f and ch. This bunch, call it b, is the size of 50 by1800 and sometimes it is 49 by 1800.

Example:

array(?,:,f_1,ch_1) = b

I wish in each loop to fill in bunch b in my array. Is there an easy way to determine "?" in each loop? Alternatively, is there an easier way to fill in "array"?

Answer 1

[Matt J]

If you want b to be inserted in the topmost rows of each array(:,:,f, ch), then it would be,

array(1:size(b,1),:,f, ch) = b 

[Haneen]

This looks good, the problem is that in the next iteration, the new b will erase the old b. I would like the "b's" to be inserted on top of each other

[Matt J]

In the next iteration, you will have a new f and ch, so each assignment will be to a new block of the array.

Answer 2

[Hiro]

repmat may solve your issue - check up the link:

repmat function

[Haneen]

repmat is for copying an array and concatinating; but here I am filling new data in every iteration. I am not sure how would repmat be of an help. Would you please elaborate?

Answer 3

[James Tursa]

Something like this maybe?

k = 1;
% your loop
    b = r x 1800 matrix
    f = whatever
    ch = whatever
    r = size(b,1);
    array(k:k+r-1,:,f,ch) = b;
    k = k + r;
% end loop

But it is not clear how f and ch change within the loop, so this might not work as written.