# Iterate an observable
**URL:** https://discourse.julialang.org/t/iterate-an-observable/89619
**Category:** Visualization
**Tags:** makie, graphs, observables
**Created:** [November 1, 2022, 3:08pm UTC](https://discourse.julialang.org/t/iterate-an-observable/89619 "2022-11-01T15:08:10Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@mgp](https://discourse.julialang.org/u/mgp)
#### Post date: [November 1, 2022, 3:08pm UTC](https://discourse.julialang.org/t/iterate-an-observable/89619/1 "2022-11-01T15:08:11Z")
I have an undirected simple graph and a vector of nodes that I want to colour red. The function `plotg` below allows this
```nohighlight
using CairoMakie, Graphs, GraphMakie
function plotg(g, y)
fig = Figure(); ax = Axis(fig[1, 1])
graphplot!(ax, g;
node_color = [ifelse(i ∈ y, :red, :black) for i ∈ vertices(g)] )
hidexdecorations!(ax); hideydecorations!(ax)
return fig
end
g = watts_strogatz(100, 4, .05; seed = 1)
red = [83, 85, 87]
plotg(g, red)
```
Now I wish to animate this, running through a vector of vectors of nodes to colour red
```julia
reds = [
[85], [85, 87], [83, 85, 87], [83, 84, 85, 87], [83, 84, 85, 87, 88],
[83, 84, 87, 88], [83, 84, 85, 87, 88], [83, 84, 85, 86, 87, 88],
[82, 83, 84, 85, 86, 87, 88], [80, 82, 83, 84, 85, 86, 87, 88],
[79, 80, 82, 83, 84, 85, 86, 87, 88], [79, 80, 82, 83, 84, 85, 86, 88]
]
```
When I try to set up an animation with `Observables`,
```julia
function videog(g, reds)
red = reds[1]
Y = Observable(red)
fig = plotg(g, Y)
record(fig, "asdf.mp4"; framerate = 2) do io
for t ∈ 1:12
red = reds[t]
Y[] = infec # change values to plot
recordframe!(io) # record a new frame
end
end
end
videog(g, reds)
```
I get an error message `MethodError: no method matching iterate(::Observable{Vector{Int64}})`.
This naive cheat gives a video but it no longer advances through the vector:
```julia
function plotg2(g, y::Vector{<:Real})
fig = Figure(); ax = Axis(fig[1, 1])
graphplot!(ax, g;
node_color = [ifelse(i ∈ y, :red, :black) for i ∈ vertices(g)] )
hidexdecorations!(ax); hideydecorations!(ax)
return fig
end
function plotg2(g, y::Observable{Vector{Int64}})
values = y[]
return plotg2(g, values)
end
function videog2(g, reds)
red = reds[1]
Y = Observable(red)
fig = plotg2(g, Y)
record(fig, "asdf.mp4"; framerate = 2) do io
for t ∈ 1:12
Y[] = reds[t] # change values to plot
recordframe!(io) # record a new frame
end
end
end
videog2(g, reds)
```
Is there a way to iterate through an `Observable` vector in an animation or do I need to find a wholly new way of making the video?
---
### Author:  [@stillyslalom](https://discourse.julialang.org/u/stillyslalom)
#### Post date: [November 1, 2022, 3:51pm UTC](https://discourse.julialang.org/t/iterate-an-observable/89619/2 "2022-11-01T15:51:57Z")
Try to work from this minimal working example with a scatter plot and a slider (just replace the slider with an `Observable` index for your video):
```julia
julia> let
pts = [(rand(2)...,) for i = 1:100]
f = Figure()
ax = Axis(f[1, 1])
sl = Slider(f[2, 1], range=eachindex(reds))
markercolor = lift(sl.value) do k
[i in reds[k] ? :red : :green for i in eachindex(pts)]
end
scatter!(ax, pts, color=markercolor)
f
end
```
---
### Author:  [@mgp](https://discourse.julialang.org/u/mgp)
#### Post date: [November 2, 2022, 4:47pm UTC](https://discourse.julialang.org/t/iterate-an-observable/89619/3 "2022-11-02T16:47:52Z")
Thank you, that helped. I now pass a vector of colours to the `plot` function and this works as an Observable.