how can i simplify this for loop?

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PJM
PJM 2013-8-8
for i=1:2 %for-loop1
for j=1:5 %for-loop2
x(j)=i;
y(j)=j+1;
t=[x; y]';
end
for j=1:5 %for-loop3
t(j,1)=t(j,1)+j;
t(j,2)=t(j,2)+2*j;
end
if i==1 %if
a=t;
elseif i>1
a=[a; t];
end
end
disp(a);
thanks for your advice and help.
---------------------------
OHHHH.. I'm sorry for my stupid question.
upper code is simplification, and
for i=1:10 %for-loop1
for j=1:11 %for-loop2
ca=Gimg(round((i-8/10)*H):round((i-2/10)*H),round((j-8/10)*W):round((j-2/10)*W));
if mean(mean(ca))<60
ca(ca>mean(mean(ca))-3)=0;
else
ca(ca<mean(mean(ca))+3)=0;
end
[x(j) y(j)]=pjm_centroid(ca);
array=[x; y]';
end
for j=1:11 %for-loop3
array(j,1)=array(j,1)+round((j-8/10)*W);
array(j,2)=array(j,2)+round((i-8/10)*H);
end
if i==1 %if
p=array;
elseif i>1
p=[p; array];
end
end
disp(p);
---------------------
this is an originally code.
variables i and j are meaningful I think.
When you compare simplification and of original code,
how can I simplify structure of for-loop in original code?

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kjetil87
kjetil87 2013-8-8
编辑：kjetil87 2013-8-8
a=[];
t=zeros(5,2);
for i=1:2
t(:,1)=(1:5)+i;
t(:,2)=(2:6)+2*(1:5);
a=[a;t];
end
disp(a)
You can also get rid of the for i=1:2 but i included it to show the process.
a=zeros(10,2);
a(:,1)=[(2:6),(3:7)];
a(:,2)=repmat((2:6)+2*(1:5),1,2); %or just hardcode
%t(:,2)=[(2:6)+2*(1:5),(2:6)+2*(1:5)]
disp(a)
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kjetil87
kjetil87 2013-8-8
Also from a closer look at your code you may have intended to move
array=[x,y]';
below the end line of for loop 2. Now you are doing 10 meaningless operations before you overwrite it again with the correct result of x and y.
PJM
PJM 2013-8-8
Thank you for your help!! :D

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更多回答（1 个）

Evan
Evan 2013-8-8
Here's how you can get rid of the nested loops:
a = [];
for i = 1:2
x(1:5) = i;
y(1:5) = (1:5) + 1;
t = [x; y]';
t(1:5,1) = t(1:5,1) + (1:5)';
t(1:5,2) = t(1:5,2) + 2*(1:5)';
a = [a; t];
end
disp(a)

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