# Looping through timeseries points of voronoi

**URL:** <https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294>\
**Category:** Visualization\
**Created:** [June 6, 2024, 7:30pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294 "2024-06-06T19:30:11Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Manasa\_S](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/manasa_s/32/209514_2.png) [@Manasa\_S](https://discourse.julialang.org/u/Manasa_S)\
**Post date:** [June 6, 2024, 7:30pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/1 "2024-06-06T19:30:11Z")

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Hi, I want to loop through the voronoi triangles, get their (x,y) cordinates and then check for the density values which i have in a form of 2d array. How can i do that?  
This is my code:

```using
using Distributions

mean_signal = [1.0, 2.0, 3.0, 4.0, 5.0, 1.0, 2, 0, 3, 0]
std_dev = [0.9, 0.2, 0.1, 0.3, 0.2, 0.3, 0.9, 0.3]

density_values = [pdf(Distributions.Normal(mean, std), x) for (mean, std) in zip(mean_signal, std_dev), x in range(0, 10, length=10)]
@show (density_values)

fig = Figure()
ax = Axis(fig[1, 1])

heatmap!(ax, density_values, colormap=:viridis)
tri = triangulate(points)
vorn = voronoi(tri)
ax2 = PlotConfig.configure_plot(fig, 1, 2, "Voronoi", "x", "y")
ax3 = PlotConfig.configure_plot(fig, 2, 1, "Centroids", "x", "y")
voronoiplot!(ax2, vorn, show_generators=false)
centroids = zeros(2, num_polygons(vorn))
for (j, i) in enumerate(each_polygon_index(vorn))
    centroids[:, j] .= DelaunayTriangulation.get_centroid(vorn, i)
end
GLMakie.scatter!(ax3, centroids)

resize_to_layout!(fig)
display(fig)

```

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<div class="post-metadata">

**Author:** ![DanielVandH](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/danielvandh/32/31134_2.png) [@DanielVandH](https://discourse.julialang.org/u/DanielVandH)\
**Post date:** [June 6, 2024, 7:41pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/2 "2024-06-06T19:41:18Z")

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Your code doesn’t run for me. I don’t think your example needs to include any plotting for this either.

1. What are Voronoi triangles? Do you mean the Voronoi cells, or are you referring to the triangles in the dual Delaunay triangulation?

2. What are the `(x, y)` coordinates associated with (assuming the answer to the above is Voronoi cells) a Voronoi cell? Do you mean its vertices, or a singular `(x, y)` value which seems to be the centroid from your example?

3. What do you mean “check for the density values”?

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<div class="post-metadata">

**Author:** ![Manasa\_S](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/manasa_s/32/209514_2.png) [@Manasa\_S](https://discourse.julialang.org/u/Manasa_S)\
**Post date:** [June 6, 2024, 8:15pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/3 "2024-06-06T20:15:58Z")

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Hi, to answer

the points is not defined, hence the code isnt running for you.

1. Yes its voronoi cells
2. (x,y) positions of the triangles and centroid
3. In the above code, i’m computing normal distribution of mean and std, now i want to check for each voronoi cells if the centroid has a density of less than 0.5, then i want to split if not delete the cell and so on.

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**Author:** ![DanielVandH](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/danielvandh/32/31134_2.png) [@DanielVandH](https://discourse.julialang.org/u/DanielVandH)\
**Post date:** [June 6, 2024, 8:25pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/4 "2024-06-06T20:25:00Z")

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The problem as described doesn’t seem fully defined so here’s some more questions.

> hence the code isnt running for you.

My point being that it’s most helpful to provide runnable code that others can work with. There’s also missing packages and I’m not sure what `PlotConfig` is

> (x,y) positions of the triangles and centroid

What triangles?

> centroid has a density of less than 0.5

What is the density of a centroid? You have a whole set of density functions there, it’s not clear to me what density you are choosing. Is the density some interpolation of those objects? Whatever the function p is that defines your density, just check p(x, y) \< 0.5 where (x, y) is the centroid I suppose.

> then i want to split if not delete the cell and so on

Not part of your question, but just incase you don’t know this step: For deleting the cell, you’ll need to use `delete_point!(tri, i)` where `tri` is the triangulation and `i` is the index of the cell. You’ll then recompute the tessellation (currently I have no implementation of e.g. `delete_cell!(vorn, i)`, it’s not hard just I haven’t done it). For splitting, I assume you mean adding in a point so e.g. `add_point!(tri, x, y)` and then again recompute the tessellation.

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<div class="post-metadata">

**Author:** ![DanielVandH](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/danielvandh/32/31134_2.png) [@DanielVandH](https://discourse.julialang.org/u/DanielVandH)\
**Post date:** [June 6, 2024, 9:12pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/6 "2024-06-06T21:12:56Z")

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It would be more helpful to try and be a bit more generic in describing in what you’re doing. Keeping the application around is making it confusing. Simple, concise, runnable code is what this is good for. What is wrong with

> Whatever the function p is that defines your density, just check p(x,y)\<0.5 where p(x,y) is the centroid I suppose.

in my reply above? You seem to define p in this last reply.

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<div class="post-metadata">

**Author:** ![Manasa\_S](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/manasa_s/32/209514_2.png) [@Manasa\_S](https://discourse.julialang.org/u/Manasa_S)\
**Post date:** [June 7, 2024, 7:30am UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/7 "2024-06-07T07:30:27Z")

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ok to get started with generic, I want to get the density values at point (x,y)

density\_values = [pdf(Distributions.Normal(mean, std), x) for (mean, std) in zip(mean\_signal, std\_dev), x in range(0, 10, length=10)]

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<div class="post-metadata">

**Author:** ![DanielVandH](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/danielvandh/32/31134_2.png) [@DanielVandH](https://discourse.julialang.org/u/DanielVandH)\
**Post date:** [June 7, 2024, 2:09pm UTC](https://discourse.julialang.org/t/looping-through-timeseries-points-of-voronoi/115294/8 "2024-06-07T14:09:47Z")

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But how are you extending the 1D density `pdf(Normal(mean, std), x)` to 2D? Are you trying to evaluate a 2D (multivariate) normal density? I don’t know what your definition of `density` is and how your values for the mean and standard deviation relate to the points in the Voronoi tessellation.

If `density` is to mean a probability density, is the probability distribution in question referring to the distribution of values inside the band in your “Uncertain time series” plot? And you want to take a point `(x, y)` inside the Voronoi tessellation and determine the density associated with that point inside the band? If so, it seems like Voronoi isn’t actually relevant here and you want to just determine how to find a probability density associated with a confidence band `mean +/- std`. Else I’m just not seeing what you are trying to compute.