How to link markers with lines in for loop

When I plot a graph using for loop with Matlab 2015a as below:

The plot look like this:

I want to connect each 'n' with line as follows:

How to do that?

Thanks..

Answer 1

[harjeet singh]

try to use this code

clear all
close all
clc

X=randint(5,100,[1 1000]);
Y=randint(1,100,[1 1000]);

for n=1:100
    x=[];
    y=[];
    for k=1:5
        x=[x X(k,n)];
        y=[y Y(1,n)];
    end
    figure(1)
    plot(y,x,'-o')
    hold on
    drawnow
end

[Stephen23]

• uses the obsolete function randint.
• very poor programming practice of expanding arrays inside a loop.
• drawnow is not required.
• loop is not required. This does the same thing, faster:

X = randi(1000,5,100);
Y = ones(5,1)*randi(1000,1,100);
plot(Y,X,'-o')

[harjeet singh]

hello stephen i just replied in the manner @mohammed asked, rest i too practicing matlab not a expert till yet

[Mohammed Sadeq]

I am not sure what you are doing @Stephen, are you here to answer the question or criticize other answers!

@harjeet, Thanks for your answer. I will accept it

[harjeet singh]

thanks @mohammed for accepting answer.

Answer 2

[Stephen23]

Solution: learn to program MATLAB code without using loops everywhere.

Although beginners think that loops are great for solving all of their problems, in fact MATLAB works best when you learn to perform your operations on all of arrays at once, in particular by writing vectorized code. So you can just pass the plot function your data matrices, and it will plot the columns of that matrix. This is clearly explained in the plot documentation.

>> X = [0.1,0.1,0.2,0.3,0.5;1.1,1.1,1.1,1.2,1.4]';
>> Y = [5,4,3,2,1;4,3,2,1,0]';
>> plot(X,Y,'-o')
>> grid on
>> legend({'one','two'})

See, no loops!

[Mohammed Sadeq]

This works with limited inputs and numbers, but I have huge data which needs the loop function to take care of it. I simplified the question to focus on the problem, but my code is much complicated which can't be simplified in a vectorized code.

Thanks..

[Stephen23]

Your data is so huge that plot cannot handle it?

Interesting, because although plot will easily handle many millions of points (I just tried 1e7), it is senseless to attempt to plot so many points:

• plotting more points than screen-pixels can show means that any extra points are just a waste of plotting power, and do not show in the final figure.
• plotting many different curves results in a figure that is impossible for any human to make sense of.

And both of these will slow down your graphics thread, etc. In general removing loops and replacing these with vectorized code will make code faster, and more expandable to larger array sizes.

What do you imagine that you will see in a figure with millions of points?

How "huge" is your data? Can you please be more specific, i.e. give us a an actual size, and tell us why you need to plot millions of points.

[Mohammed Sadeq]

@Stephen, I believe you didn't understand my problem and your last comment prove it. Anyway, thanks for trying..