How do I get values out of a scatter plot that are in between the data points

Ok, so I have a dataset with a column of x values and a column of y values. I have plotted them as a scatter plot here.

What I want to do is extract x values for a given y value. E.g. what are the x values when y = 17? As you can see, a given y value might not actually have a "plotted" x value.

Answer 1

[Image Analyst]

You could try spline() or interp1(). See attached demo.

Red points are the original "knots" and the blue points are the interpolated points.

You can maybe reverse the x and y and plug the y into spline to get the x.

Or else make a few million interpolated points and use ismembertol(), though there may be a more direct and accurate way such as finding the two points on either side of hte y value and using bilinear interpolation.

[Usama Ahmed]

Thank you for your very detailed answer! But when I now try to find corresponding x-values to y values, I get an error. Using this code:

DesiredX = interp1(yData, xData, DesiredY)

Where DesiredY is my input y for which i want the corresponding x values (stored in DesiredX).

I get a "The grid vectors must contain unique points" error.

[Image Analyst]

Please remember to attach your data. Make it easy for people to help you, not hard. I'll check back later today.

[Usama Ahmed]

I've attached the data I'm using as well as the code. DataAnalyis1 contains the code. DataVariables contains the data I'm using.