plotting a horizontal line at each data point

How to plot a horizontal line at each co-ordinate.Here consider 1a,1b, 1c etc as horizontal points, energy values as vertical points.Also how to indicate which color is used for which.pls help.

[Ilian]

This is not an elegant solution but you can probably solve this with a loop and line()

Answer 1

[Star Strider]

Try this:

x = 1:10;                                               % Create Data
yh = rand(size(x))-2;                                   % Create Data
yl = rand(size(x))-4;                                   % Create Data

hl = @(x,y,l,c) plot(x+[-l l], y*[1 1],c);              % Anonymous Function To Draw Horizontal Lines

figure
hold on
for k = 1:numel(x)
    hl(x(k),yh(k),0.5,'b')
    hl(x(k),yl(k),0.5,'r')
    text(x(k),yh(k), sprintf('%5.2f',yh(k)), 'VerticalAlignment','bottom', 'HorizontalAlignment','center')
    text(x(k),yl(k), sprintf('%5.2f',yl(k)), 'VerticalAlignment','top', 'HorizontalAlignment','center')
    text(x(k),yh(k),'\uparrow', 'VerticalAlignment','top', 'HorizontalAlignment','center')
    text(x(k),yl(k),'\downarrow', 'VerticalAlignment','bottom', 'HorizontalAlignment','center')
    text(x(k), mean([yh(k) yl(k)]), sprintf('%5.2f',(yh(k)-yl(k))), 'VerticalAlignment','middle', 'HorizontalAlignment','center')
    plot([1 1]*x(k),[yl(k) yh(k)+sign(yh(k))*0.1], '-k', 'LineWidth',0.5)
end
yl = ylim;
ylim(yl+[-1 1]*0.2)

.

[P Rakesh Kumar Dora]

If i want to put specific "y" values,then how can i do this?

THANKS

[Star Strider]

My pleasure!

I am not certain what you are asking. In my code, ‘yh’ are the higher y-values and ‘yl’ are the lower y-values. I have no idea what your data are, so you would have to separate them into those vectors to use my code.

If you provide your x and y data, I can (probably) change my code to accommodate them.

Also, I forgot about the x-tick labels. Use this call:

set(gca, 'XTick',x, 'XTickLabel',{'1a' '1b' '1c' '2a' '2b' '2c' '3a' '3b' '3c'})

after the plotting loop to set them.

And use this ‘x’ vector with my code and those x-tick labels:

x = 1:9;                                                % Create Data

.

[P Rakesh Kumar Dora]

I have the following data.Also pls can you indicate which color is used for ' yh' and which for 'yl' like my first fig.on right side of the plot.

THANKS.

[Star Strider]

My pleasure!

The ‘c’ (fourth) argument in the ‘hl’ anonymous function denotes the line color:

hl = @(x,y,l,c) plot(x+[-l l], y*[1 1],c);              % Anonymous Function To Draw Horizontal Lines

so calling it in the loop:

hl(x(k),yh(k),0.5,'b')
hl(x(k),yl(k),0.5,'r')

uses blue ('b') for ‘yh’ and red ('r') for ‘yl’, since that is how they are plotted in the image you posted. The line lengths are 1 in this example (going from -0.5 to +0.5 with respect to ‘x’). The third (‘l’) argument controls that. It can be anything you want.

The rest of the code prints the labels for the horizontal lines and y-value differences, and plots the arrowheads and the vertical lines connecting them.

.

[P Rakesh Kumar Dora]

Thanks a lot.

[Star Strider]

As always, my pleasure!

[P Rakesh Kumar Dora]

Pls can you tell me how to insert legend in the above plot.Like 'red line' corresponds to 'homo' and 'blue line'

corresponds to 'lumo' .Thanks.

[Star Strider]

As always, my pleasure!

There are two ways to do that.

The first simply reverses the order of the legend arguments (with no other changes in the code), adding this line at the end:

legend('LUMO', 'HOMO')

The second requires returning the handles of the red and blue lines:

    hu = hl(x(k),yh(k),0.5,'b');
    hd = hl(x(k),yl(k),0.5,'r');

(with no changes in the rest of the code) and then at the end adding:

legend([hd hu], 'HOMO', 'LUMO')

Both of these work. Choose the one that you prefer.

.

[P Rakesh Kumar Dora]

Thanks.

[Star Strider]

As always, my pleasure!

Answer 2

[Steven Lord]

My first thought when I saw your picture was errorbar.