Filling matrix with cell arrays in a loop leaves all rows empty except the last one

Hi,

I was wondering if someone would be able to explain what is causing data to be lost from my matrix (except the last row) when I run it through a loop? My problem is much like this person's:

https://www.mathworks.com/matlabcentral/answers/491536-storing-data-in-cell-array-using-for-loop

However, I already created the cell array outside the loop using matrix = cell(48,1); and am still getting this issue. I'm not doing anything with the matrix in the loop except this:

matrix(i) = {[Var1 Var2 Var3]};

I'm assuming there's an issue with my syntax in this line of code, but I can't seem to find a solution to this anywhere.

Thanks in advance!

[VBBV]

However, I already created the cell array outside the loop using matrix = cell(48,1); and am still getting this issue.

Thats unlikely to have any issue, The problem in the link that you sent, is that of declaration of cell array inside the loop,

% declared outside the loop as in your case
dataBase=cell(3,3);
for n=1:3
    
    t = randi([0 10],1,1);
    
    while (t<3 || t>6)
        t = randi([3 6],1,1);
        
    end
        alpha = ([0:pi/t:2.*pi]);
        
    si = sin(alpha);
    co = cos(alpha);
    
    M =[rad2deg(alpha); si ; co]';
    
    x=M(:,1)';
    ys=M(:,2)';
    yc=M(:,3)';
    
    dataBase{n,1}=x;
    dataBase{n,2}=ys;
    dataBase{n,3}=yc;
end
dataBase

dataBase = 3×3 cell array
    {[0 36 72 108 144 180 216 252 288 324 360]}    {[0 0.5878 0.9511 0.9511 0.5878 1.2246e-16 -0.5878 … ]}    {[1 0.8090 0.3090 -0.3090 -0.8090 -1 -0.8090 -0.3090 … ]}
    {[        0 45 90 135 180 225 270 315 360]}    {[ 0 0.7071 1 0.7071 1.2246e-16 -0.7071 -1 -0.7071 … ]}    {[1 0.7071 6.1232e-17 -0.7071 -1 -0.7071 -1.8370e-16 … ]}
    {[0 36 72 108 144 180 216 252 288 324 360]}    {[0 0.5878 0.9511 0.9511 0.5878 1.2246e-16 -0.5878 … ]}    {[1 0.8090 0.3090 -0.3090 -0.8090 -1 -0.8090 -0.3090 … ]}

Answer 1

[VBBV]

% place this line outside of all loops 
matrix = cell(48,1);

matrix{i} = [Var1 Var2 Var3];

[VBBV]

Try like this instead, Also check whether the

matrix = cell(48,1);

is outside of ALL loops. if its present inside another nested loop , theni its likely the same issue as in the link you sent.

[Leeza]

Thank you for your response. Yes, matrix = cell(48,1); is outside of all the loops, so I'm not sure what the issue is. Are there maybe any other ways that I can create an empty matrix and populate it with a loop? Or are there any other possible issues you can think of that could be causing this error?

[Leeza]

UPDATE: I fixed it, turns out I was assuming that the 'i' represented the range that I needed, which it did not. Thank you for attempting to help me anyway!

[VBBV]

ok, did you do something like this ?

% declared outside the loop as in your case
dataBase=cell(3,3);
n = 1:3;
for i = n
    
    t = randi([0 10],1,1);
    
    while (t<3 || t>6)
        t = randi([3 6],1,1);
        
    end
        alpha = ([0:pi/t:2.*pi]);
        
    si = sin(alpha);
    co = cos(alpha);
    
    M =[rad2deg(alpha); si ; co]';
    
    x=M(:,1)';
    ys=M(:,2)';
    yc=M(:,3)';
    
    dataBase(i) = {[x ys yc]};
end
dataBase

dataBase = 3×3 cell array
    {[0 36 72 108 144 180 216 252 288 324 360 0 0.5878 0.9511 … ]}    {0×0 double}    {0×0 double}
    {[0 60.0000 120.0000 180 240.0000 300 360 0 0.8660 0.8660 … ]}    {0×0 double}    {0×0 double}
    {[0 36 72 108 144 180 216 252 288 324 360 0 0.5878 0.9511 … ]}    {0×0 double}    {0×0 double}