# If statement in a for loop

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MarshallSc on 27 Aug 2021
Answered: Wan Ji on 27 Aug 2021
I have a 4*4 array, that each contains a 10*10 matrix. I want to assign a value to the components that are bigger than 1. I wrote the code below but the array still gives me the old answer. I my code correct?
for i=1:4
for j=1:4
for k=1:10
for r=1:10
if A{i,j}(k,r)> 1
A{i,j}(k,r)=0.25;
end
end
end
end
end

Chunru on 27 Aug 2021
Edited: Chunru on 27 Aug 2021
There is no problem on your code.
% Generate some data
A0 = mat2cell(randn(40,40), [10 10 10 10], [10 10 10 10])
A0 = 4×4 cell array
{10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double} {10×10 double}
A = A0;
for i=1:4
for j=1:4
for k=1:10
for r=1:10
if A{i,j}(k,r)> 1
A{i,j}(k,r)=0.25;
end
end
end
end
end
A0{1,1}
ans = 10×10
-0.6734 0.8692 -1.6546 1.2093 -0.1341 -1.0695 -0.8146 2.6268 -1.6082 -0.1045 -1.2485 0.0057 -1.4931 -1.4591 -0.6572 2.0670 -1.0974 -1.5611 0.2182 -0.1246 1.8132 -0.0679 -1.3699 1.2575 0.2293 0.1918 0.6182 1.6094 -0.8047 0.5807 1.1543 -0.5832 1.1783 -0.7724 0.1431 -0.2715 0.5826 -0.0001 0.9344 0.2417 -0.0182 -0.3490 0.9430 -0.1741 -0.3922 -0.4503 -0.5467 -0.6232 -0.4263 0.1276 -0.0209 0.4221 1.1669 -0.3341 -1.6741 -0.6565 0.5037 -0.0330 -0.4805 0.0410 0.7771 0.1379 0.3202 -0.8057 -1.0736 -0.2393 -0.0838 0.6039 0.9621 0.3609 0.5417 0.7622 -1.3825 -1.2397 -0.1665 -0.7916 -0.2269 1.4506 -0.1991 -1.7380 0.8511 0.5444 -1.6257 1.8856 -0.4868 -0.7078 -0.6926 0.4313 -1.4832 1.0208 0.9372 -0.9295 1.3307 1.0626 0.9382 -1.3204 0.0972 1.0081 -0.2195 -1.8600
A{1,1} % compare A0 and A1 to see the value of 0.2500
ans = 10×10
-0.6734 0.8692 -1.6546 0.2500 -0.1341 -1.0695 -0.8146 0.2500 -1.6082 -0.1045 -1.2485 0.0057 -1.4931 -1.4591 -0.6572 0.2500 -1.0974 -1.5611 0.2182 -0.1246 0.2500 -0.0679 -1.3699 0.2500 0.2293 0.1918 0.6182 0.2500 -0.8047 0.5807 0.2500 -0.5832 0.2500 -0.7724 0.1431 -0.2715 0.5826 -0.0001 0.9344 0.2417 -0.0182 -0.3490 0.9430 -0.1741 -0.3922 -0.4503 -0.5467 -0.6232 -0.4263 0.1276 -0.0209 0.4221 0.2500 -0.3341 -1.6741 -0.6565 0.5037 -0.0330 -0.4805 0.0410 0.7771 0.1379 0.3202 -0.8057 -1.0736 -0.2393 -0.0838 0.6039 0.9621 0.3609 0.5417 0.7622 -1.3825 -1.2397 -0.1665 -0.7916 -0.2269 0.2500 -0.1991 -1.7380 0.8511 0.5444 -1.6257 0.2500 -0.4868 -0.7078 -0.6926 0.4313 -1.4832 0.2500 0.9372 -0.9295 0.2500 0.2500 0.9382 -1.3204 0.0972 0.2500 -0.2195 -1.8600
% However the code can be simplified.
A2 = cellfun(@changevalue, A0, 'UniformOutput', false);
A2{1,1}
ans = 10×10
-0.6734 0.8692 -1.6546 0.2500 -0.1341 -1.0695 -0.8146 0.2500 -1.6082 -0.1045 -1.2485 0.0057 -1.4931 -1.4591 -0.6572 0.2500 -1.0974 -1.5611 0.2182 -0.1246 0.2500 -0.0679 -1.3699 0.2500 0.2293 0.1918 0.6182 0.2500 -0.8047 0.5807 0.2500 -0.5832 0.2500 -0.7724 0.1431 -0.2715 0.5826 -0.0001 0.9344 0.2417 -0.0182 -0.3490 0.9430 -0.1741 -0.3922 -0.4503 -0.5467 -0.6232 -0.4263 0.1276 -0.0209 0.4221 0.2500 -0.3341 -1.6741 -0.6565 0.5037 -0.0330 -0.4805 0.0410 0.7771 0.1379 0.3202 -0.8057 -1.0736 -0.2393 -0.0838 0.6039 0.9621 0.3609 0.5417 0.7622 -1.3825 -1.2397 -0.1665 -0.7916 -0.2269 0.2500 -0.1991 -1.7380 0.8511 0.5444 -1.6257 0.2500 -0.4868 -0.7078 -0.6926 0.4313 -1.4832 0.2500 0.9372 -0.9295 0.2500 0.2500 0.9382 -1.3204 0.0972 0.2500 -0.2195 -1.8600
% a local function
function x = changevalue( x)
x(x>1) = 0.25;
end

KSSV on 27 Aug 2021
[m,n] = size(A) ;
iwant = cell(m,n);
for i = 1:m
for j = 1:n
T = A{i,j} ;
T(T>1) = 0.25 ;
iwant{i,j} = T ;
end
end

Wan Ji on 27 Aug 2021
You can do like this
A = mat2cell(rand(40,40)+0.5, [10 10 10 10], [10 10 10 10]);
% A is your data randomly generated, you can put yours there
[i,j] = meshgrid((1:size(A,1)), (1:size(A,2)));
B = arrayfun(@(i,j)A{i,j}-A{i,j}.*(A{i,j}>1) + 0.25*(A{i,j}>1), i, j, 'uniform',0); % B is what you want
Or you can do like this
A = cell2mat(A);
A(A>1) = 0.25;
A = mat2cell(A,10*ones(4,1),10*ones(4,1)); % the final is what you want