How can I join points within a plot with a line?

I have this plot that consistes of five vector points with one minimun and one maximum each one. I want to automatically draw a line to join all the maximum points, and all the minimum points horizontally.

I am proceding the following way,

clc,clear

 b = datestr(datenum(now),1);

 for k1 = 1:5

    x(k1) = datenum(addtodate(datenum(b), k1, 'day'));

 end
 xs = datestr(x,1)
 x;

 y1 = max([5,10]);
y2 = max([5,10]);
y3 = max([12,17]);
y4 = max([12,16]);
y5 = max([12,17]);

 y8 = min([5,10]);
y9 = min([5,10]);
y10 = min([12,17]);
y11 = min([12,16]);
y12 = min([12,17]);

 plot(x(1),y1,'-- ys','LineWidth',2,'MarkerEdgeColor','r','MarkerFaceColor','g','MarkerSize',10)       
hold on 
plot(x(1),y8,'--ys','LineWidth',2,'MarkerEdgeColor','b','MarkerFaceColor','y','MarkerSize',10)        
plot(x(2),y2,'-- ys','LineWidth',2,'MarkerEdgeColor','r','MarkerFaceColor','g','MarkerSize',10)       
plot(x(2),y9,'--ys','LineWidth',2,'MarkerEdgeColor','b','MarkerFaceColor','y','MarkerSize',10)        
plot(x(3),y3,'-- ys','LineWidth',2,'MarkerEdgeColor','r','MarkerFaceColor','g','MarkerSize',10)       
plot(x(3),y10,'--ys','LineWidth',2,'MarkerEdgeColor','b','MarkerFaceColor','y','MarkerSize',10)        
plot(x(4),y4,'-- ys','LineWidth',2,'MarkerEdgeColor','r','MarkerFaceColor','g','MarkerSize',10)       
plot(x(4),y11,'--ys','LineWidth',2,'MarkerEdgeColor','b','MarkerFaceColor','y','MarkerSize',10)        
plot(x(5),y5,'-- ys','LineWidth',2,'MarkerEdgeColor','r','MarkerFaceColor','g','MarkerSize',10)       
plot(x(5),y12,'--ys','LineWidth',2,'MarkerEdgeColor','b','MarkerFaceColor','y','MarkerSize',10)       

 datetick('x',1,'keepticks');

 title('Wind(Knots) versus Time (dd-mmmm-yyyy)','fontsize',12,'fontweight','b','fontname','times');
xlabel('Time (dd-mmmm-yyyy)','fontweight','b','fontname','times');
ylabel('Wind (Knots)','fontweight','b','fontname','times');
set(gca,'fontname','times')
grid minor

Once again, I want to draw a horizontal line from the first maximum including all the points all the way untill the last number, and the same for the minimum points.

Can you please help?

Answer 1

[Azzi Abdelmalek]

ymin=[y8 y9 y10 y11 y12 ];
ymax=[y1 y2 y3 y4 y5];
plot(x,ymin,'--ys','LineWidth',2,'MarkerEdgeColor','r',...
    'MarkerFaceColor','g','MarkerSize',10)       
hold on 
plot(x,ymax,'--ys','LineWidth',2,'MarkerEdgeColor','r',...
    'MarkerFaceColor','g','MarkerSize',10)