# Trees in Julia
**URL:** https://discourse.julialang.org/t/trees-in-julia/12173
**Category:** New to Julia
**Tags:** question, tree
**Created:** [July 5, 2018, 1:21am UTC](https://discourse.julialang.org/t/trees-in-julia/12173 "2018-07-05T01:21:47Z")
**Posts on this page:** 15
**Page:** 1
### Author:  [@microlifecc](https://discourse.julialang.org/u/microlifecc)
#### Post date: [July 5, 2018, 1:21am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/1 "2018-07-05T01:21:47Z")
Hi Guys!
I am new to Julia and am trying to learn by writing some code. So I was trying to implement a tree and get the sum of node of all the elements in the sub-tree given a particular node.
Here is my work:
```julia
struct element
name::String
data::Int64
loe
end
F1 = element("F1", 1, nothing)
F2 = element("F2", 2, nothing)
F3 = element("F3", 3, nothing)
D4 = element("D4", 0, [F1, F2])
D5 = element("D5", 0, [F3])
D6 = element("D6", 0, [D4, D5])
function sum_data_loe(loe)
if loe == nothing
0
else
(length(loe)>1)?(sum_data_element(loe[1]) + sum_data_loe[2:end]):sum_data_element(loe[1])
end
end
function sum_data_element(e)
if e.data == 0
sum_data_loe(e.loe)
else
e.data
end
end
@test sum_data_element(F1) == 1 #Test Passed
@test sum_data_loe(nothing) == 0 #Test Passed
@test sum_data_element(D5) == 3 #Test Passed
@test sum_data_element(D4) == 3 #Failed
@test sum_data_element(D6) == 6 #Failed
```
Error:
> Error During Test
> Test threw an exception of type MethodError
> Expression: sum\_data\_element(D4) == 3
> MethodError: no method matching endof(::#sum\_data\_loe)
> Closest candidates are:
> endof(::SimpleVector) at essentials.jl:257
> endof(::Char) at char.jl:18
> endof(::String) at strings/string.jl:153
> …
> Stacktrace:
> [1] sum\_data\_loe(::Array{element,1}) at ./In[9]:5
> [2] sum\_data\_element(::element) at ./In[10]:3
> [3] include\_string(::String, ::String) at ./loading.jl:522
> [4] execute\_request(::ZMQ.Socket, ::IJulia.Msg) at /home/subhankar/.julia/v0.6/IJulia/src/execute\_request.jl:158
> [5] (::Compat.#inner#18{Array{Any,1},IJulia.#execute\_request,Tuple{ZMQ.Socket,IJulia.Msg}})() at /home/subhankar/.julia/v0.6/Compat/src/Compat.jl:378
> [6] eventloop(::ZMQ.Socket) at /home/subhankar/.julia/v0.6/IJulia/src/eventloop.jl:8
> [7] (::IJulia.##14#17)() at ./task.jl:335
> There was an error during testing
> Stacktrace:
> [1] record(::Base.Test.FallbackTestSet, ::Base.Test.Error) at ./test.jl:533
> [2] do\_test(::Base.Test.Threw, ::Expr) at ./test.jl:352
---
### Author:  [@JackDevine](https://discourse.julialang.org/u/JackDevine)
#### Post date: [July 5, 2018, 1:34am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/2 "2018-07-05T01:34:42Z")
It looks like you tried to index into a function in the `else` part of `sum_data_loe`. All of the tests pass for me if I replace `sum_data_loe[2:end]` with `sum_data_loe(loe[2:end]))`.
---
### Author:  [@microlifecc](https://discourse.julialang.org/u/microlifecc)
#### Post date: [July 5, 2018, 1:50am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/3 "2018-07-05T01:50:49Z")
Thanks a lot!!!
---
### Author:  [@swissr](https://discourse.julialang.org/u/swissr)
#### Post date: [July 5, 2018, 9:20am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/4 "2018-07-05T09:20:51Z")
> [@microlifecc](#):
>
> I am new to Julia … Here is my work:
>
> ```julia
> struct element
> ...
>
> ```
A bit nitpicking maybe, but `element` is a type and should begin with a _capital letter_. See here for the conventions: [https://docs.julialang.org/en/latest/manual/variables/#Stylistic-Conventions-1](https://docs.julialang.org/en/latest/manual/variables/#Stylistic-Conventions-1). Of course you are free to do what you want 😉
[Edit]: ah, and the variables F1, F2, … D6 should be in lower case, i.e. f1, f2, … d6.
---
### Author:  [@wookyoung](https://discourse.julialang.org/u/wookyoung)
#### Post date: [July 5, 2018, 11:35am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/5 "2018-07-05T11:35:15Z")
As you might know already, there are Julia packages for data structures such as
[https://github.com/Keno/AbstractTrees.jl](https://github.com/Keno/AbstractTrees.jl) [GitHub - JuliaCollections/DataStructures.jl: Julia implementation of Data structures](https://github.com/JuliaCollections/DataStructures.jl)
Try this in Julia 0.7
```julia
struct Element
name::String
data::Int64
loe
end
F1 = Element("F1", 1, nothing)
F2 = Element("F2", 2, nothing)
F3 = Element("F3", 3, nothing)
D4 = Element("D4", 0, [F1, F2])
D5 = Element("D5", 0, [F3])
D6 = Element("D6", 0, [D4, D5])
import AbstractTrees: children, printnode, print_tree, Leaves
children(el::Element) = something(el.loe, [])
sum_data_element(el::Element) = sum(map(x->x.data, Leaves(el)))
using Test
@test sum_data_element(F1) == 1
@test sum_data_element(D5) == 3
@test sum_data_element(D4) == 3
@test sum_data_element(D6) == 6
printnode(io::IO, el::Element) = print(io, el.name, ' ', el.data)
print_tree(D6)
```
---
### Author:  [@kapple](https://discourse.julialang.org/u/kapple)
#### Post date: [July 11, 2019, 7:53am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/6 "2019-07-11T07:53:23Z")
Hi @microlifecc, have you finished your code and successfully created the tree diagram?
I can’t find any Julia/Matlab/LaTeX solutions for how to make a nice tree?
Anyone know how to make a tree diagram?
---
### Author:  [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)
#### Post date: [July 11, 2019, 9:04am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/7 "2019-07-11T09:04:21Z")
> **[GitHub - JuliaPlots/GraphRecipes.jl: Graph-related recipes to be used with...](https://github.com/JuliaPlots/GraphRecipes.jl)**
>
> Graph-related recipes to be used with Plots.jl. Contribute to JuliaPlots/GraphRecipes.jl development by creating an account on GitHub.
---
### Author:  [@kapple](https://discourse.julialang.org/u/kapple)
#### Post date: [July 11, 2019, 10:44am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/8 "2019-07-11T10:44:09Z")
Wanna help me out? It’s ugly.
```julia
using GraphRecipes
using Plots
edges = [[1, 2, 3] ,[2, 4, 5], [3, 6, 7], [5, 8, 9]]
N = maximum(maximum.(edges)) + 1
A = zeros(N, N)
for n = 1:length(edges)
r = edges[n][1]
for c in edges[n][2:end]
A[r, c] = 1
end
end
A += A'
graphplot(A,
node_weights = 1:N,
names = 1:N,
linecolor = :darkgrey)
```
---
### Author:  [@BeastyBlacksmith](https://discourse.julialang.org/u/BeastyBlacksmith)
#### Post date: [July 11, 2019, 11:57am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/9 "2019-07-11T11:57:17Z")
I think it looks a bit nicer when using the `pyplot`-backend. So
```julia
using Plots
pyplot()
```
---
### Author:  [@kapple](https://discourse.julialang.org/u/kapple)
#### Post date: [July 12, 2019, 12:49am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/10 "2019-07-12T00:49:46Z")
Thanks!
Though, I want to plot a tree-structured view.
I might start making it from scratch.
---
### Author:  [@chakravala](https://discourse.julialang.org/u/chakravala)
#### Post date: [July 12, 2019, 2:46am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/11 "2019-07-12T02:46:47Z")
> **[GitHub - JuliaTeX/TreeView.jl: Draw Julia syntax trees as a graph](https://github.com/JuliaTeX/TreeView.jl)**
>
> Draw Julia syntax trees as a graph. Contribute to JuliaTeX/TreeView.jl development by creating an account on GitHub.
---
### Author:  [@kapple](https://discourse.julialang.org/u/kapple)
#### Post date: [July 12, 2019, 4:15am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/12 "2019-07-12T04:15:43Z")
Yeah I’ve seen this too.
It’s for Syntax trees, and not really for general tree-diagram plotting.
---
### Author:  [@chakravala](https://discourse.julialang.org/u/chakravala)
#### Post date: [July 12, 2019, 4:26am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/13 "2019-07-12T04:26:12Z")
It’s for AST, but also a good starting point for LaTeX plotting other kinds of tree types.
---
### Author:  [@mhw](https://discourse.julialang.org/u/mhw)
#### Post date: [July 14, 2019, 2:36am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/14 "2019-07-14T02:36:00Z")
Hi kapple,
you can generate really nice trees with LuaLaTeX if you are using the Tikz package, especially \usetikzlibrary{graphdrawing} and \usegdlibrary{trees}. Here is a LaTeX-file as an example. This example has included Lua code which is necessary when using Windows. The indentations in the Lua code are important (layout rule)!
```julia
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{graphdrawing}
\usepackage{luacode}
\begin{luacode}
function pgf_lookup_and_require(name)
local sep = '/'
if string.find(os.getenv('PATH'),';') then
sep = '\string\\'
end
local function lookup(name)
local sub = name:gsub('%.',sep)
local find_func = function (name, suffix)
if resolvers then
local n = resolvers.findfile (name.."."..suffix, suffix) -- changed
return (not (n == '')) and n or nil
else
return kpse.find_file(name,suffix)
end
end
if find_func(sub, 'lua') then
require(name)
elseif find_func(sub, 'clua') then
collectgarbage('stop')
require(name)
collectgarbage('restart')
else
return false
end
return true
end
return
lookup('pgf.gd.' .. name .. '.library') or
lookup('pgf.gd.' .. name) or
lookup(name .. '.library') or
lookup(name)
end
\end{luacode}
\usetikzlibrary{graphs}
\usegdlibrary{trees}
\begin{document}
\input{t.tex};
\end{document}
```
The Tex-file t.tex contains the data for generating the tree layout. This file is generated by a small Julia program which I have written for trees with Int values and with arbitrary many childs.The program can easily be adapted to other (generic) tree data structures
```julia
struct IntTree
node :: Int64
childs :: Array{IntTree,1}
end
leaf(x:: Int64) = IntTree(x,[])
isLeaf(t:: IntTree) = t.childs == []
oneChild(t:: IntTree) = length(t.childs) == 1
tree(x:: Int64, ts:: Array{IntTree,1}) = IntTree(x,ts)
# examples for type Tree
l1 = leaf(1)
l2 = leaf(64)
l3 = leaf(17)
l4 = leaf(9)
t1 = tree(11,[l1,l2])
t2 = tree(4,[l3,l4])
t3 = tree(6,[l1,l2,l4])
t4 = tree(21,[t1,t3,l3])
function drawTree(r:: IntTree)
if (isLeaf(r))
return string(r.node)
elseif (oneChild(r))
return string(r.node) * " -- " * drawTree(r.child[1])
else
xs = map( drawTree, r.childs )
return string(r.node) * " -- " * "{ " * join(xs, ", ") * " }"
end
end
function tree2Latex(t:: IntTree, fileName:: String)
s1 = "\\begin{tikzpicture}[every node/.style={circle, draw, minimum size=0.75cm}] \n\n "
s2 = "\\graph [tree layout, grow=down, fresh nodes, level distance=0.5in, sibling distance=0.5in] \n {"
s3 = " };\n \\end{tikzpicture}"
s = s1 * s2 * drawTree(t) * s3
outfile = open(fileName, "w")
write(outfile, s)
close(outfile)
end
```
If you want the tree diagram of the tree t4 in the Julia code above then first execute
> tree2Latex(t4, “t.tex”)
> and then compile the above given LaTeX source with lualatex. Here is the result
> 
---
### Author:  [@kapple](https://discourse.julialang.org/u/kapple)
#### Post date: [July 15, 2019, 11:59am UTC](https://discourse.julialang.org/t/trees-in-julia/12173/15 "2019-07-15T11:59:31Z")
That’s very kind of you, thank you.
I’ll give them a shot.
Edit: It would be amazing if we had Julia instead of Lua with Tex documentation in the future. Weave documentation lacks so many features. It’s nice though.