How Do I make this plot faster?

I am trying to make this plot, but it is taking too much time. How do I make this plot faster?

Fs = 2500;          % Hz 
t = 0:1/Fs:4;       % a vector that represents 1 second, sampled at Fs

indices = [1, 0.001*Fs+1, 0.002*Fs+1, 0.004*Fs+1, 0.008*Fs+1, 0.01*Fs+1];
indices = round(indices); % ensure integer indices

y = zeros(0.02*2500+1, 10001);
% This makes the y with only needed indices.
for k = 1:length(indices)
    y(indices(k), indices(k)) = 1; % single "1" at the right position
end

%0.001 is not existing in the t array, so we make it rounded up so that we
%can print it out.
t_x = t(1:0.02*2500+1);
% This is for the t array
figure;
stem(t_x,y);
xlabel('time');
ylabel('vectors');
legend('e1','e4','e6','e11','e21','e26')
grid on;
axis normal;
% This is for printing out the unit vectors.

Also, when I plot out, the legend does not seems to match. Here is the plot

Aother question is that why t_x seems to be 1*51 and y seems to be 51*10001. Why does this works but when I use t_x and y', it does not work?

Answer 1

[Walter Roberson]

You are plotting a 51 x 10001 array. That is slow.

Most of what is being plotted is all zeros. There is not a lot of point in plotting the all-zero entries (at least not more than one of them.)

tic
Fs = 2500;          % Hz 
t = 0:1/Fs:4;       % a vector that represents 1 second, sampled at Fs

toc

Elapsed time is 0.005135 seconds.

tic
indices = [1, 0.001*Fs+1, 0.002*Fs+1, 0.004*Fs+1, 0.008*Fs+1, 0.01*Fs+1];
indices = round(indices); % ensure integer indices
toc

Elapsed time is 0.002060 seconds.

tic
y = zeros(0.02*2500+1, 10001);
% This makes the y with only needed indices.
for k = 1:length(indices)
    y(indices(k), indices(k)) = 1; % single "1" at the right position
end
toc

Elapsed time is 0.002936 seconds.

tic
%0.001 is not existing in the t array, so we make it rounded up so that we
%can print it out.
t_x = t(1:0.02*2500+1)';
toc

Elapsed time is 0.001035 seconds.

whos t_x y

  Name       Size                 Bytes  Class     Attributes

  t_x       51x1                    408  double              
  y         51x10001            4080408  double              

tic
% This is for the t array
figure;
stem(t_x,y);
xlabel('time');
ylabel('vectors');
legend('e1','e4','e6','e11','e21','e26')
grid on;
axis normal;

% This is for printing out the unit vectors.
toc

Elapsed time is 20.778554 seconds.