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

**URL:** https://discourse.julialang.org/t/how-do-i-load-a-vector-of-strings-into-a-balltree-in-nearestneighbors-jl/33950
**Category:** General Usage
**Tags:** machine-learning
**Created:** [January 29, 2020, 9:57pm UTC](https://discourse.julialang.org/t/how-do-i-load-a-vector-of-strings-into-a-balltree-in-nearestneighbors-jl/33950 "2020-01-29T21:57:46Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![mthelm85](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mthelm85/32/224164_2.png) [@mthelm85](https://discourse.julialang.org/u/mthelm85)
#### Post date: [January 29, 2020, 9:57pm UTC](https://discourse.julialang.org/t/how-do-i-load-a-vector-of-strings-into-a-balltree-in-nearestneighbors-jl/33950/1 "2020-01-29T21:57:46Z")

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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:

```julia
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.

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<div class="post-metadata">

### Author: ![mthelm85](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mthelm85/32/224164_2.png) [@mthelm85](https://discourse.julialang.org/u/mthelm85)
#### Post date: [January 30, 2020, 6:54pm UTC](https://discourse.julialang.org/t/how-do-i-load-a-vector-of-strings-into-a-balltree-in-nearestneighbors-jl/33950/2 "2020-01-30T18:54:26Z")

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In case anyone else wants to do this, someone else already figured all this out and it’s pretty amazing. See [VPTrees.jl](https://github.com/altre/VPTrees.jl).