Question on setfields

New to Julia
1

I have a weird setfields use case:

p = Normal(1,2);
setproperties(p, μ=0.5)

works but I would like to do

a=:μ;
setproperties(p, a=0.5)

such that I can pass a to a function…how do I do that?

2

You can use Pair syntax for this

julia> function foo(;a =1)
       return a
       end
foo (generic function with 1 method)

julia> x = :a
:a

julia> foo(; x => 5)
5
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3

Are you sure that can be used with setfields for changing a struct?

4

Edit: See answer above.

5

Does it work? If it’s a keyword argument it should work. Though I dont know what package setproperties is from so its hard to help

1 Like
6

No, I don’t get it to work. Setproperties is from the package Setfield

7 
julia> using Distributions, Setfield, NamedTupleTools

julia> p = Normal(1, 2)
Normal{Float64}(μ=1.0, σ=2.0)

julia> x = :μ;

julia> setproperties(p, namedtuple((x,), (0.5,)))
Normal{Float64}(μ=0.5, σ=2.0)
2 Likes
8

These are already great answers. As @hendri54 noted, you can also pass NamedTuples to setproperties:

julia> using ConstructionBase # or using Setfield, if you like
julia> dist = (μ=10, σ=20, α=30);
julia> patch = (μ=1, α=2);
julia> setproperties(dist, patch)
(μ = 1, σ = 20, α = 2
julia> a = :μ; patch = (;a => 100,)
(μ = 100,)
julia> setproperties(dist, patch)
(μ = 100, σ = 20, α = 30)
2 Likes