Select 100 points either side from mouse click cooradinates

Need help!!

I have a line graph. I would like to get 100 points either side of the plot from mouse click coordinate.

I was looking at bsxfun fucntion

bsxfun(@plus,xcoods(:,2),-100:100) Can be used ?

I am using 2016a matlab version

[Rik]

It doesn't sound like that would help you.

Can you confirm the following is what you mean?

You have a line graph. The user clicks somewhere in the axes, the coordinate being recorded with a function like getpts. Now you want 100 points of your graph directly to left of the click coordinate and 100 points of your graph to the right of the click coordinate?

[Kurni Eswar]

Exactly, This is want I what

[Adam]

What is wrong with the simplest possible answer:

xCoord + ( -100:100 );

? You can just repmat the y coordinate 201 times.

[Kurni Eswar]

It works

Thanks

Answer 1

[KSSV]

x = linspace(0,1) ; 
y = sqrt(x) ; 
% Mid point
M = [mean(x) mean(y)] ; 
% points left side 
idx1 = x<M(1) ; 
% % points right side 
idx2 = x>M(1) ;

figure
hold on
plot(x,y,'r') ; 
plot(x(idx1),y(idx1),'.b')
plot(x(idx2),y(idx2),'.g')

legend('data','left points','right points')

Answer 2

[Rik]

Use the x-coordinate returned by getpts to select the data.

x=linspace(0,10,1000);
%generate a smooth random curve
y=sin(x)+polyval([0.01 0.1 1 10].*rand(1,4),x);

figure(1),clf(1)%only use clf during debugging
plot(x,y,'b','DisplayName','Data')

[xp,yp]=getpts;
if numel(xp)<1
    clc,error('no points selected')
else
    xp=xp(1);
end

pos_left=find(x<xp,100,'last');%might not return 100 points
pos_right=find(x>xp,100,'first');%might not return 100 points

hold on
plot(x(pos_left),y(pos_left),'.r','DisplayName','Left of click')
plot(x(pos_right),y(pos_right),'.g','DisplayName','Left of click')
hold off
legend