# How do I load a vector of Strings into a BallTree in NearestNeighbors.jl?

I’m trying to figure out how to load a vector of strings into a BallTree from NearestNeighbors.jl and I could really use some guidance. From what I understand, I can create my own Metric and use it with a BallTree so here’s what I have so far:

``````using Distances
using NearestNeighbors

# Create a new metric...and then what?
struct Levenshtein <: Metric end

# Function that computes the edit distance between two strings
function levenshtein(s::AbstractString, t::AbstractString)
n,m = length(s), length(t)
s,t = n < m ? (s,t) : (t,s)
n,m = n < m ? (n,m) : (m,n)
n == 0 && return m
m == 0 && return n
d = reshape(zeros(Int8, (m+1)*(n+1)), m+1, n+1)
d[:,1], d[1,:] = collect(0:m), collect(0:n)
for i in 1:n, j in 1:m
cost = s[i] == t[j] ? 0 : 1
d[j+1, i+1] = min(d[j,i+1]+1, d[j+1,i]+1, d[j,i]+cost)
end
return d[m+1, n+1]
end
``````

Unfortunately, I’m already stumped . The function works just fine but I don’t know what the next step is to be able to wire this all together so that I can load a vector of strings into the tree, structure the tree according to the Levenshtein Metric, and then query the tree afterwords with new strings that aren’t in it.

In case anyone else wants to do this, someone else already figured all this out and it’s pretty amazing. See VPTrees.jl.