For loop for function values

Hey everyone,

I've been trying to improve my coding lately with for loops, but I'm sturggling to figure this one out.

Here's the original code. BW2_BW refers to an image and the row's all refer to image coordinates.

R1 = imcrop(BW2_BW, [row_1]);
R2 = imcrop(BW2_BW, [row_2]);
R3 = imcrop(BW2_BW, [row_3]);
R4 = imcrop(BW2_BW, [row_4]);
R5 = imcrop(BW2_BW, [row_5]);

stats_BW_R1 = regionprops(R1,'Centroid');
stats_BW_R2 = regionprops(R2,'Centroid');
stats_BW_R3 = regionprops(R3,'Centroid');
stats_BW_R4 = regionprops(R4,'Centroid');
stats_BW_R5 = regionprops(R5,'Centroid');

This is what I'm trying to do:

for k = 1:5
    stats_BW_R(k) = regionprops(R(k),'Centroid');
end

I basically want k to replicate values 1:5 to replace what my original code did. What am I doing wrong?

Thanks!

[Stephen23]

"What am I doing wrong?"

Numbering some variables and then trying to access the variable names dynamically.

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Answer 1

[madhan ravi]

stats_BW_R = cell(1,5);
for k = 1:5    
    R = imcrop(BW2_BW, rows{k}); % rows = [row_1,...row_5]
    stats_BW_R{k} = regionprops(R,'Centroid');
end

[DP]

Okay, for the rows function, do you create a cell or a double? I did as you commented and I get the error Brace indexing is not supported for variables of this type.

[madhan ravi]

rows = {row_1,...row_5}

You need to learn the basics of MATLAB.

[DP]

I agree

[madhan ravi]

And make sure to read the comment of Fangjun and Stephens.

Answer 2

[Fangjun Jiang]

Don't create variables R1, R2, ... R5. Instead, create array R, use R(1), R(2), ... R(5). Then you can run your for-loop.