How can I do to avoid using eval?
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Hi! I'm modifying a code created with Matlab but I have a problem: I'd like to avoid using the eval function and at the same time create arrays that contain a variable number of elements.
For example, in this part of code
num_int = 3;
for k = 1 : num_int
eval(['m = length(I',num2str(k),')'])
for i = 1 : m
if count_vector(k) == 0
eval(['ydata_low_',num2str(k),'(i,:) = [I',num2str(k),'_0(i) I',num2str(k),'_1(i) I',num2str(k),'_2(i) I',num2str(k),'_3(i) I',num2str(k),'_4(i)]']);
eval(['ydata_high_',num2str(k),'(i,:) = [I',num2str(k),'_5(i) I',num2str(k),'_6(i) I',num2str(k),'_7(i) I',num2str(k),'_8(i)]']);
end
end
I should create ydata_low and ydata_high, in function of k (that is num_int and is worth is 3).
In short, six arrays should be created: ydata_low_1, ydata_low_2, ydata_low_3, ydata_high_1, ydata_high_2 and ydata_high_3. The program already creates the variables to be introduced into the matrices (see attachment). I'd also like that variables from I_0 to I_4 are inserted in data_low and the variables from I_5 to I_8 are inserted in data_high.
Thank you!!
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Guillaume
2018-9-17
The code to fix is not the one you show unfortunately, It's the code before that which creates all these numbered I variables.
Do not create numbered variables. Matlab already has a way of storing together things with an index: matrices and cell arrays. Instead of all these Ix_y you should have a single I variable (and a better, more meaningful name wouldn't hurt) that is a cell array with I{1} a 3121x10 matrix, |I{2} a 3554x10 matrix, and I{3} and 3510x10 matrix (each made by horizontally concatenating [Ix, Ix_0, ..., Ix_9]. With that your correct code is trivial:
num_int = numel(I); %no more hardcoded size
for k = 1:num_int
if count_vector(k) == 0
y_data_low{k} = I{k}(:, 2:5);
y_data_high{k} = I{k}(:, 6:10);
end
end
To be honest, there isn't even a need for y_data_low and y_data_high since it's simply I{k}(:, 2:5) and I{k}(:, 6:10) respectively.
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