How to find a y value given the x on a plot?

Hello!

My current problem is I'm trying to achieve a plot like this:

But all I have is the blue plot and the x's of the values I want to scatter plot on the line. I was wondering if there was a way to get the y values from the plot.

I tried idexing the blue signal with che x's, but it gives me an ''index must be positive integers'' error.

Can anyone help me with that?

Answer 1

[Star Strider]

Use interpolation, specifically interp1 here.

Without your data, an illustration would be something like this —

x = linspace(-5, 5, 50);
y = sinc(x);

xv = 10*rand(3,1)-5                                         % Arbitrary 'x' Values

xv = 3×1

2.0330 -0.3249 -2.3227

yv = interp1(x, y, xv, 'linear')                            % Corresp[inding 'y' Values

yv = 3×1

0.0129 0.8317 0.1136

figure
plot(x, y)
grid
hold on
plot(xv, yv, 'p')
hold off

.

[Elena Dipalma]

Thank you so much!

I had came across this type of solution but couldn't seem to undestand how to implement it.

I finally managed thanks to you.

Have a wonderful day!

[Star Strider]

As alkways, my pleasure!

I appreciate your compliment.

You have a wonderful day, too!