How to inherit values from for loop into if else loop?

Question

Tinna Armasamy 2017-4-25

0
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https://ww2.mathworks.cn/matlabcentral/answers/337133-how-to-inherit-values-from-for-loop-into-if-else-loop

编辑： Walter Roberson 2017-4-26

This is my code :

for i=1:n
    Area(i)=k(i).Area;
    Diameter(i)=sqrt(4*[k(i).Area]/pi);
    MajorAxis(i)=k(i).MajorAxisLength;
end

Now I want to use the MajorAxis value into if else loop. Eg :-

if MajorAxis(i) < 0.002
    Clay(i)=MajorAxis(i);
end

But the (i) values from for loop are not being inherited.

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Tinna Armasamy 2017-4-25

编辑：Walter Roberson 2017-4-26

i mean that the i values are not performing the if else loop

Jan 2017-4-25

This is unclear: "i values not performing the if else loop". I cannot imagine, what this should mean. There is neither an "if else loop", nor do loop counters "perform" anything - most of all not outside the loop.

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Answer 1

Jan 2017-4-25

0
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https://ww2.mathworks.cn/matlabcentral/answers/337133-how-to-inherit-values-from-for-loop-into-if-else-loop#answer_264392

在 MATLAB Online 中打开

There is no magic "inheriting" of loop counters. I think the main problem is hiddon in your formulation "if else loop": The if command is not a loop.

You have to include the if into the loop:

Area      = zeros(1, n);  % Pre-allocate!
Diameter  = zeros(1, n);
MajorAxis = zeros(1, n);
Clay      = zeros(1, n);
for i=1:n
  Area(i)      = k(i).Area;
  Diameter(i)  = sqrt(4*[k(i).Area]/pi);
  MajorAxis(i) = k(i).MajorAxisLength;
  if MajorAxis(i) < 0.002
    Clay(i) = MajorAxis(i);
  end
end

Or you can omit the loop:

Area      = [k.Area];
Diameter  = sqrt(4 * Area / pi);
MajorAxis = [k.MajorAxisLength];
Clay      = zeros(1, n);
Index     = (MajorAxis < 0.002);
Clay(Index) = MajorAxis(Index);

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Tinna Armasamy 2017-4-26

编辑：Walter Roberson 2017-4-26

在 MATLAB Online 中打开

soilgray=getimage(handles.axes1);
soilgray=rgb2gray(soilgray);
level=graythresh(soilgray);
im=im2bw(soilgray,level);
axes(handles.axes2);
imshow(im);
cc = bwconncomp(im,8);
n= cc.NumObjects;
set(handles.text11,'String',n);
Area = zeros(n,1);
Diameter = zeros(n,1);
MajorAxis = zeros(n,1);
Clay=zeros(1,n);
Silt=zeros(1,n);
Sand=zeros(1,n);
k = regionprops(cc,'Area','EquivDiameter','MajorAxisLength');
for i=1:n
      Area(i)      = k(i).Area;
    Diameter(i)  = sqrt(4*[k(i).Area]/pi);
    MajorAxis(i) = k(i).MajorAxisLength;
     Diameter(i) = (Diameter(i)*25.4)/300;
       if      Diameter(i) < 0.002
               Diameter(i)=Clay(i);
          else if Diameter(i) >=0.002 && Diameter(i) < 0.05
               Diameter(i)=Silt(i);
          else if Diameter(i) >= 0.05 && Diameter(i) < 2
               Diameter(i)=Sand(i);
              end
              end
       end
  end
NumC = numel(Clay);
             ClayPercentage = (NumC/n)*100;
             set(handles.text15,'String',ClayPercentage);
            NumC = numel(Silt);
               SiltPercentage = (NumC/n)*100;
               set(handles.text16,'String',SiltPercentage);
                NumC = numel(Sand);
               SandPercentage = (NumC/n)*100;
               set(handles.text17,'String',SandPercentage);