# Any examples of how to rotate a grid of points?
**URL:** https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211
**Category:** New to Julia
**Created:** [October 22, 2021, 1:29pm UTC](https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211 "2021-10-22T13:29:34Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)
#### Post date: [October 22, 2021, 1:29pm UTC](https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211/1 "2021-10-22T13:29:34Z")
I found two packages of interest Rotations.jl and ReferenceFraneRotations.jl - does anyone happen to know an example where it is used to rotate for example a grid of points 45 degrees? I have found a function to generate a grid like this:
```julia
function creategrid(d::Integer, dp::Number)
@assert d >= 1 ("d (number of dimensions) must be a positive integer")
r = range(-1, 1, step = dp)
iter = Iterators.product((r for _ in 1:d)...)
return vec([collect(i) for i in iter])
end
creategrid(2,0.1)
```
Kind regards
---
### Author:  [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)
#### Post date: [October 22, 2021, 3:09pm UTC](https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211/2 "2021-10-22T15:09:43Z")
Since you have 2D grids and seemingly simple rotations, it may be more instructive to write the rotation matrix in this case:
```julia
rotgrid(grd, θ) = [cos(θ) -sin(θ); sin(θ) cos(θ)] * grd
grd = creategrid(2, 0.05)
rgrd = rotgrid.(grd, π/4)
using GLMakie
scene = scatter(first.(grd), last.(grd), color=:blue, markersize=5, axis=(aspect=DataAspect(), ))
scatter!(first.(rgrd), last.(rgrd), color=:red, markersize=5)
```
---
### Author:  [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)
#### Post date: [October 25, 2021, 5:09pm UTC](https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211/3 "2021-10-25T17:09:32Z")
Thanks for this suggestion!
If I would want to do the rotation around a specific point, let us say the bottom right corner, how would I do that?
Kind regards
---
### Author:  [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)
#### Post date: [October 25, 2021, 5:19pm UTC](https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211/4 "2021-10-25T17:19:20Z")
To rotate around any point `P0`:
You can do:
```julia
grd = creategrid(2, 0.05)
P0 = [-1,-1] # point of rotation
rgrd = rotgrid.(grd .- Ref(P0), π/4) .+ Ref(P0)
```
---
### Author:  [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)
#### Post date: [October 25, 2021, 5:44pm UTC](https://discourse.julialang.org/t/any-examples-of-how-to-rotate-a-grid-of-points/70211/5 "2021-10-25T17:44:57Z")
Thank you very much Rafael 🙂
Kind regards