# Truncating and re-saving a Mesh (in .stl format)
**URL:** https://discourse.julialang.org/t/truncating-and-re-saving-a-mesh-in-stl-format/49860
**Category:** New to Julia
**Tags:** meshio
**Created:** [November 9, 2020, 6:48pm UTC](https://discourse.julialang.org/t/truncating-and-re-saving-a-mesh-in-stl-format/49860 "2020-11-09T18:48:24Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Alan\_Bahm](https://discourse.julialang.org/u/Alan_Bahm)
#### Post date: [November 9, 2020, 6:48pm UTC](https://discourse.julialang.org/t/truncating-and-re-saving-a-mesh-in-stl-format/49860/1 "2020-11-09T18:48:24Z")
I would like to load a .stl file of triangular facets, remove most from the mesh and save as a new .stl file.
```julia
using FileIO, MeshIO
mesh = load("test.stl")
using GeometryBasics
new_mesh = Mesh(mesh[1:3]) # grab first three triangles
save("test_out.stl", new_mesh)
```
The code above fails with a method error. Other more detailed forms of setting up a new Mesh from the old have also met with issues deeper in GeometryBasics, so I must be missing something.
What is the accepted approach? Can someone provide a short working example of this?
Thanks!
---
### Author:  [@sdanisch](https://discourse.julialang.org/u/sdanisch)
#### Post date: [November 9, 2020, 7:09pm UTC](https://discourse.julialang.org/t/truncating-and-re-saving-a-mesh-in-stl-format/49860/2 "2020-11-09T19:09:33Z")
Can you help by making the example reproducible?
What’s the method error?
It looks good in theory, but maybe just some wrongly ordered arguments or so… or a bug!
```nohighlight
new_mesh = Mesh(mesh[1:3])
```
This could work, but is definitely untested 😉
---
### Author:  [@Alan\_Bahm](https://discourse.julialang.org/u/Alan_Bahm)
#### Post date: [November 9, 2020, 9:03pm UTC](https://discourse.julialang.org/t/truncating-and-re-saving-a-mesh-in-stl-format/49860/3 "2020-11-09T21:03:00Z")
> [@Alan\_Bahm](#):
>
Thanks for the quick reply Simon! This code :
```julia
open("test.stl", "w") do io
write(io, "solid \n")
write(io, " facet normal 1.0 1.0 1.0\n")
write(io, " outer loop\n")
write(io, " vertex 1.0 0.0 0.0\n")
write(io, " vertex 0.0 1.0 0.0\n")
write(io, " vertex 0.0 0.0 1.0\n")
write(io, " endloop\n")
write(io, " endfacet\n")
write(io, " facet normal 1.0 1.0 1.0\n")
write(io, " outer loop\n")
write(io, " vertex 2.0 0.0 0.0\n")
write(io, " vertex 0.0 2.0 0.0\n")
write(io, " vertex 0.0 0.0 2.0\n")
write(io, " endloop\n")
write(io, " endfacet\n")
write(io, " facet normal 1.0 1.0 1.0\n")
write(io, " outer loop\n")
write(io, " vertex 3.0 0.0 0.0\n")
write(io, " vertex 0.0 3.0 0.0\n")
write(io, " vertex 0.0 0.0 3.0\n")
write(io, " endloop\n")
write(io, " endfacet\n")
write(io, "endsolid \n")
end
using FileIO, MeshIO
mesh = load("test.stl")
using GeometryBasics
new_mesh = Mesh(mesh[1:2]) # grab first two triangles
save("test_out.stl", new_mesh)
```
will produce this error :
```julia
Error encountered while saving "test_out.stl".
Fatal error:
ERROR: LoadError: MethodError: no method matching coordinates(::Mesh{3,Float32,GeometryBasics.Ngon{3,Float32,3,PointMeta{3,Float32,Point{3,Float32},(:normals,),Tuple{Vec{3,Float32}}}},Array{GeometryBasics.Ngon{3,Float32,3,PointMeta{3,Float32,Point{3,Float32},(:normals,),Tuple{Vec{3,Float32}}}},1}})
Closest candidates are:
coordinates(::GeometryBasics.Ngon) at /home/user/.julia/packages/GeometryBasics/csguK/src/basic_types.jl:73
coordinates(::LineString) at /home/user/.julia/packages/GeometryBasics/csguK/src/basic_types.jl:187
coordinates(::TupleView) at /home/user/.julia/packages/GeometryBasics/csguK/src/viewtypes.jl:39
...
Stacktrace:
[1] handle_error(::MethodError, ::File{DataFormat{:STL_ASCII}}) at /home/user/.julia/packages/FileIO/2fEu2/src/error_handling.jl:82
[2] handle_exceptions(::Array{Any,1}, ::String) at /home/user/.julia/packages/FileIO/2fEu2/src/error_handling.jl:77
[3] save(::Formatted, ::Any; options::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /home/user/.julia/packages/FileIO/2fEu2/src/loadsave.jl:238
[4] save at /home/user/.julia/packages/FileIO/2fEu2/src/loadsave.jl:217 [inlined]
[5] #save#19 at /home/user/.julia/packages/FileIO/2fEu2/src/loadsave.jl:139 [inlined]
[6] save(::String, ::Mesh{3,Float32,GeometryBasics.Ngon{3,Float32,3,PointMeta{3,Float32,Point{3,Float32},(:normals,),Tuple{Vec{3,Float32}}}},Array{GeometryBasics.Ngon{3,Float32,3,PointMeta{3,Float32,Point{3,Float32},(:normals,),Tuple{Vec{3,Float32}}}},1}}) at /home/user/.julia/packages/FileIO/2fEu2/src/loadsave.jl:139
[7] top-level scope at /home/user/mesh_save_error.jl:36
[8] include(::String) at ./client.jl:439
[9] top-level scope at REPL[1]:1
in expression starting at /home/user/mesh_save_error.jl:36
```
on Julia v1.4.1 with recent packages :
```julia
...
[5789e2e9] FileIO v1.4.4
...
[5c1252a2] GeometryBasics v0.3.3
...
[7269a6da] MeshIO v0.4.3
...
```