Intersection of two plots

[Desmond]

I have two lines on a plot and I want Julia to find the intersection between the two lines but I can’t seem to find a package that can help with that.

[nilshg]

see

Mark the Intersection Points on a Plot Graph

Some example code for computing the intersection of curves from discrete data points using polynomial fits. This code blocks creates some artificial data. using Polynomials, Plots # two functions that intersect on an interval (a,b) f1(x) = 2x + 12 f2(x) = x^2 (a,b) = (2,7) # the interval of interest n = 10 # number of data points ynoise = 0.3 # noise level, absolute # create some noisy data from those two functions x = range(a, b, length=n) y1 = f1.(x) + ynoise*randn(n) y2 …

[nilshg]

or even:

Find intersection between curves in julia

Hello, I have two curves with the values: col_y = [8.02511788606e7, 9.98481296252e7, 2.328332483329e8, 6.148181496526e8, 9.453171952624e8, 1.2331292887706e9, 1.4394296796998e9, 1.460066157955e9, 1.3570403824485e9, 1.4269447174002e9] vin_y = [1.434628836798e8, 1.318375623746e8, 1.108524843855e8, 6.91176196241e7, 4.19137382458e7, 1.48676444645e7, 1.00659726053e7, 7.8734512643e6] Is it possible to find the intersection x between these two curves? what is the approach in julia? Thank you

[joa-quim]

The GMT fill_between function uses the gmtspatial module to do that.

https://www.generic-mapping-tools.org/GMTjl_doc/examples/plotting_functions/02_1filledlines/#fill_between

[math4mad]

Idea

basically, if we don’t have explicit function expression, the curve is a set of data
simplify way is link two points to segment ,then check whether two segment intersect
this is naive method.
But I thought this is not a simple question, for numerical method, neighbors are problem

step

• package Meshes.jl for Segment method Intersection

  using Meshes
  s1 = Segment((0.0,0.0), (1.0,0.0))
  s2 = Segment((0.5,0.0), (2.0,0.0))
  inst=s1 ∩ s2
  

typeof(inst)==Point2

if segment does’nt intersect, then return nothing

• make data

• iterate to find intersection point

---

code

---

using Meshes

step = 100
xspan = range(-2, 2, step)
arr = []
d1 = [(x, x^2) for x in xspan] .|> (d -> (round(d[1], digits=4), round(d[2], digits=4)))
d2 = [(x, 2 * x) for x in xspan] .|> (d -> (round(d[1], digits=4), round(d[2], digits=4)))

for i in 1:step-1

    local s1 = Segment(d1[i], d1[i+1])
    local s2 = Segment(d2[i], d2[i+1])
    local bool = s1 ∩ s2 |> d -> (typeof(d) == Point2)
    (bool == true) && push!(arr, res)
end

arr