MATLAB: In an assignment A(I) = B, the number of elements in B and I must be the same.

assignmentdebugging skillserror

    clc
x=25;
y=25;
for i=1:10
r=rand;
if r<=0.25
    x(i) =x+1
elseif r<=0.5 && r>0.25
    y=y+1
else if r<=0.75 && r>0.5
        x=x-1
    else 
        y=y-1
    end
end
x=x;
y=y;
end
comet(x,y)
plot(x,y)
  end
The above code generates the error:
In an assignment A(I) = B, the number of elements in B and I must be the same.
Error in xy (line 7)
    x(i) =x+1
Can you please help me in modifying the code in right way so that I can balance the vectors.
I am really sorry for asking this kind of question again and again as I have seen the repetitions, but it was a failure to gain the correct answer. Thank You.

Best Answer

Try
x(i) = x(i) + 1;
Full Demo:
clc;
clearvars;
close all;
workspace;
format longg;
format compact;
fontSize = 16;
numberOfSteps = 10;
r = rand(numberOfSteps, 1);
x = zeros(numberOfSteps, 1);
y = zeros(numberOfSteps, 1);
x(1) = 25; % Starting location.

y(1) = 25; % Starting location.
subplot(2, 2, 3:4);
hold on;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
drawnow;
for k = 2 : numberOfSteps
  if r(k) <= 0.25
    x(k) = x(k-1) + 1 % Move x by 1.

    y(k) = y(k-1); % No change;



  elseif r(k) <= 0.5 && r(k) > 0.25
    x(k) = x(k-1); % No change;
    y(k) = y(k-1) + 1 % Move y by 1.

  elseif r(k) <= 0.75 && r(k) > 0.5
    x(k) = x(k-1) - 1 % Move x by 1.
    y(k) = y(k-1); % No change;
  else
    x(k) = x(k-1); % No change;
    y(k) = y(k-1) - 1 % Move y by 1.
  end
  text(x(k)+0.05, y(k), num2str(k), 'fontSize', fontSize);
end
subplot(2, 2, 1:2);
comet(x,y);
grid on;
title('Comet', 'fontSize', fontSize);
subplot(2, 2, 3:4);
plot(x, y, 'bs-', 'LineWidth', 2);
title('Plot', 'fontSize', fontSize);
grid on;
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