Connecting dots with straight line in a loop.

Asked by Tatte Berklee on 20 Oct 2019

Latest activity Answered by Image Analyst on 20 Oct 2019

12 views (last 30 days)

Hi all,

I have a question regarding connecting the dots.

Suppose I have the following sample data points:

I have a while-loop that identifies the first, second, and fourth points in the figure.

I know their index numbers and their (x,y) values.

Pictorially, I would like to connect with a straight line, the aforementioned points.

What is the best way of doing this?

My gut feeling is to input the "draw" code within the while-loop I have so each time I obtain the index of the next point I want to connect, I simply connect to that pictorially. But how to go about this?

Thanks in advance!

0 Comments

Products

MATLAB

Release

R2019b

3 Answers

Link

Answer by darova on 20 Oct 2019

Just use plot function

plot(x(index),y(index))

2 Comments

Tatte Berklee on 20 Oct 2019

Hi! But how does the plot make the dots connect? Not only do I want the dots appear on the plot but also connect to the subsequent dot I obtain.

darova on 20 Oct 2019

If you have data (x,y) and it's order just use plot

x = rand(1,4);
y = rand(1,4);
index = [1 4 2 3];
plot(x(index),y(index))

Link

Answer by ABHILASH SINGH on 20 Oct 2019

Follow this code.

https://in.mathworks.com/matlabcentral/fileexchange/57185-cognitive-radio-frequency-assignment-with-interference-technique-conflict-graph

0 Comments

Link

Answer by Image Analyst on 20 Oct 2019

It seems that no one is exactly sure what you want to do, since the super obvious plot(x,y,'b-') doesn't seem to be it.

So I'll throw out a couple of guesses.

To close the figure (if that's what you want) you can tack the first point onto the array:

xp = [x, x(1)];
yp = [y, y(1)];
plot(xp, yp, 'b.-', 'LineWidth', 2, 'MarkerSize', 18);
grid on;

To make a bunch of points in between, you'd have to use polyfit and polyval() for each segment. Here it is for one segment with endpoints (x1, y1) and (x2, y2):

numNewPoints = 100; % Whatever you want.
newx = linspace(x1, x2, numNewPoints);
y = linspace(y1, y2, numNewPoints);
coefficients = polyfit([x1,x2], [y1, y2], 1);
newY = polyval(coefficients, newx);

You are now following this question

Tatte Berklee (view profile)