# LightOSM: precomputing dijkstra\_states throws an UndefVarError

**URL:** <https://discourse.julialang.org/t/lightosm-precomputing-dijkstra-states-throws-an-undefvarerror/89551>\
**Category:** Geo\
**Created:** [October 31, 2022, 9:59am UTC](https://discourse.julialang.org/t/lightosm-precomputing-dijkstra-states-throws-an-undefvarerror/89551 "2022-10-31T09:59:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ctrebbau](https://avatars.discourse-cdn.com/v4/letter/c/5f9b8f/32.png) [@ctrebbau](https://discourse.julialang.org/u/ctrebbau)\
**Post date:** [October 31, 2022, 9:59am UTC](https://discourse.julialang.org/t/lightosm-precomputing-dijkstra-states-throws-an-undefvarerror/89551/1 "2022-10-31T09:59:41Z")

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From [LightOSM.jl/benchmarks.jl at master · DeloitteOptimalReality/LightOSM.jl · GitHub](https://github.com/DeloitteOptimalReality/LightOSM.jl/blob/master/benchmark/benchmarks.jl)

```julia
point = GeoLocation(-37.8142176, 144.9631608) # Melbourne, Australia
radius = 5 # km
data_file = joinpath(@ __DIR__ , "benchmark_map.osm")

g_losm = LightOSM.graph_from_download(:point,
                                      point=point,
                                      radius=radius,
                                      weight_type=:distance,
                                      download_format=:osm,
                                      save_to_file_location=data_file)

# g_losm = LightOSM.graph_from_file(data_file, weight_type=:distance)
@time g_losm_precompute = LightOSM.graph_from_file(data_file, weight_type=:distance, precompute_dijkstra_states=true)

```

throws and UndefVarError blaming a parameter `n` in `src/graph.jl:455` which simply initialises a vector to hold ` g.dijkstra_states = Vector{Vector{U}}(undef,n)`  
Shouldn’t this be `g.dijkstra_states = Vector{Vector{U}}(undef,length(g.nodes))` ?

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<div class="post-metadata">

**Author:** ![visr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/visr/32/17204_2.png) [@visr](https://discourse.julialang.org/u/visr)\
**Post date:** [October 31, 2022, 10:26am UTC](https://discourse.julialang.org/t/lightosm-precomputing-dijkstra-states-throws-an-undefvarerror/89551/2 "2022-10-31T10:26:39Z")

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I think you’re right. I’d click the edit button on [LightOSM.jl/graph.jl at 33898b9b45728878546ac22775347e7ae2459dd2 · DeloitteOptimalReality/LightOSM.jl · GitHub](https://github.com/DeloitteOptimalReality/LightOSM.jl/blob/33898b9b457288/src/graph.jl#L456) and propose the change 🙂