For Loop and indexing - matlab

Question

Following is my code :
function marks(my_numbers)
handle = zeros(5,1)
x = 10 ;
y = 10:20:100 ;
for i = 1
for j = 1:5 ;
handle(j,i) = rectangle('position',[x(i),y(j),20 10],'facecolor','r')
end
end
end
now lets say input argument my_numbers = 2
so i have written the code :
set(handle(j(my_numbers),1),'facecolor','g')
With this command, rectangle with lower left corner at (30,10) should have turned green. But MATLAB gives an error of index exceeds matrix dimensions

Answer 1

This is more an illustrated comment than an answer, but as #hagubear mentioned your i index is pointless so you could remove it altogether.
Using set(handle(my_numbers,1),'facecolor','g') will remove the error, because you were trying to access handles(j(2),1) and that was not possible because j is a scalar.
Anyhow using this line after your plot works fine:
set(handle(my_numbers,1),'facecolor','g')
According to your comment below, here is a way to call the function multiple times and add green rectangles as you go along. There are 2 files for the purpose of demonstration, the function per se and a script to call the function multiple times and generate an animated gif:
1) The function:
function marks(my_numbers)
%// Get green and red rectangles to access their properties.
GreenRect = findobj('Type','rectangle','FaceColor','g');
RedRect = findobj('Type','rectangle');
%// If 1st call to the function, create your plot
if isempty(RedRect)
handle = zeros(5,1);
x = 10 ;
y = 10:20:100 ;
for j = 1:5 ;
handle(j) = rectangle('position',[x,y(j),20 10],'facecolor','r');
end
set(handle(my_numbers,1),'facecolor','g')
%// If not 1st call, fetch existing green rectangles and color them green. Then color the appropriate rectangle given by my_numbers.
else
RedRect = flipud(RedRect); %// Flip them to maintain correct order
if numel(GreenRect) > 0
hold on
for k = numel(GreenRect)
set(GreenRect(k),'facecolor','g')
set(RedRect(my_numbers,1),'facecolor','g')
end
end
end
2) The script:
clear
clc
%// Shuffle order for appearance of green rectangles.
iter = randperm(5);
filename = 'MyGifFile.gif';
for k = iter
marks(k)
pause(1)
frame = getframe(1);
im = frame2im(frame);
[imind,cm] = rgb2ind(im,256);
if k == iter(1)
imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
else
imwrite(imind,cm,filename,'gif','WriteMode','append');
end
end
Here is the animated gif of the output: