connecting every two endpoints

Hi all, I have the following formula that allow me to plot 2D points calculated from a text file.

plot(endpnts(:,1),scyendpnts,'sr', 'MarkerSize',5,'MarkerFaceColor', 'b', 'MarkerEdgeColor', 'none');   %plot all endpoints a red dots

plot(endpnts(R,1),scyendpnts(R),'sr', 'MarkerSize',5, 'MarkerFaceColor', 'b', 'MarkerEdgeColor', 'none');

I'm trying to also connect the points two by two with a line, like (4:1) with (5:1), (6:1) with (7:1) and so on but can't figure out how - by using the statement bellow I can draw a line between all points.

hold on; 

plot(endpnts(:,1),scyendpnts,'LineWidth',2, 'MarkerFaceColor','b');  

plot(endpnts(R,1),scyendpnts,'LineWidth',2, 'MarkerFaceColor','b')

I thank you in advance

Tarsis

Answer 1

[Walter Roberson]

plot(endpnts(:,1),scyendpnts,'sr', 'MarkerSize',5,'MarkerFaceColor', 'b', 'MarkerEdgeColor', 'none');

is enough to draw lines between each pair of points, with red square markers.

I am not sure what more you want done? Do you want a line connecting the last point to the first? If so then

plot(endpoints([1:end 1],1), scyendpnts([1:end 1]), 'sr', 'MarkerSize',5,'MarkerFaceColor', 'b', 'MarkerEdgeColor', 'none');

Are you trying to connect every point to every other point, so point 4 is connected to point 1, 2, 3, 5, 6, etc?

[tarsis]

Hi Walter,

Thank you so much for your anwser! I'm trying to connect point 4 to point 5, point 6 to point 7 and so on.

But not between those (there should be no connection between 5 and 6, 7 and 8, etc).

Thank again.

[Walter Roberson]

x = reshape(endpnts(:,1), 2, []);
y = reshape(scyendpnts, 2, []);
plot(x, y, 'sr', 'MarkerSize',5,'MarkerFaceColor', 'b', 'MarkerEdgeColor', 'none');

[tarsis]

Hi Walter, thanks a lot.

Just one more question, is there a way for this plot start from endopoint 4 instead of 1?

Thank a lot

Tarsis

[Walter Roberson]

x = reshape(endpnts(4:end,1), 2, []);
y = reshape(scyendpnts(4:end), 2, []);

Just watch out that the number of remaining points is even (so the number of original points must be odd); if it is not then the above code will crash trying to match up the last entry.

[tarsis]

Awesome, thanks again.

Answer 2

[Seyedfarid Ghahari]

Hi,

Is there any automatic way to connect points to each other as 1 to 2, 3 to 4, 5 to 6, ... without using for. In other words, I have Xi, Yi, Zi and Xj, Yj, and Zj vectors which contain X, Y, and Z coordinates of start (i) and end (j) of many lines. I would like to draw these lines, but if I use:

plot3([Xi,Xj],[Yi,Yj],[Zi,Zj])

Matlab connects all lines, while I want to have all lines disconnected!

[Walter Roberson]

That is what my answer above does: reshape into columns of length 2, and MATLAB will draw each column as a distinct line.

[Seyedfarid Ghahari]

By doing this, all points are connected in series. That is, 1 is connected to 2, 2 to 3, 3 to, ... while I do not want any connection between 2 and 3 or between 4 and 5 etc. I figured it out: I used NaN at every two points;)