Question

I have two arrays x, y with coordinates of a function.

Example:

x=[0,1,2,3,4,5]
y=[0,1,5,20,30,32]

pylab.plot(x,y) shows me a smooth function for this.

Is there a way to get the x-Value for y=3?

regards

Answer 1

You should be able to use numpy.interp for this.

e.g.:

numpy.interp(3.,y,x)  #1.5

Note that this only works since your y values are monotonic. If your y-values aren’t monotonic, there is no guarantee that your mapping of y->x is unique.