setval! is being weird

[torfjelde]

So I'm currently making a PR for generated_quantities, and ran into the following:

julia> using DynamicPPL, Turing

julia> Turing.turnprogress(false);
[ Info: [Turing]: progress logging is disabled globally
[ Info: [AdvancedVI]: global PROGRESS is set as false

julia> @model function demo_fails(xs, ::Type{TV} = Vector{Float64}) where {TV}
           m = TV(undef, 2)
           for i in 1:2
               m[i] ~ Normal(0, 1)
           end

           for i in eachindex(xs)
               xs[i] ~ Normal(m[1], 1.)
           end

           return (m, )
       end;

julia> xs = randn(3);

julia> model_fails = demo_fails(xs);

julia> chain_fails = sample(model_fails, NUTS(0.65), 100);
┌ Info: Found initial step size
└   ϵ = 1.6

julia> var_info = VarInfo(model_fails);

julia> spl = SampleFromPrior();

julia> θ_0 = var_info[spl]
2-element Array{Float64,1}:
 -0.34786841389137324
  0.4703320351984347

julia> res_0 = model_fails(var_info, spl)
([-0.34786841389137324, 0.4703320351984347],)

julia> DynamicPPL.setval!(var_info, chain_fails, 1, 1);

julia> θ_1 = var_info[spl] # <= note that the value has changed since `θ_0`
2-element Array{Float64,1}:
 -0.34786841389137324
  0.4703320351984347

julia> res_1 = model_fails(var_info, spl) # <= has NOT changed since `res_0`!!!
([-0.34786841389137324, 0.4703320351984347],)
 ...

In contrast, the following works just fine:

julia> @model function demo_works(xs)
           m ~ MvNormal(2, 1.)
           for i in eachindex(xs)
               xs[i] ~ Normal(m[1], 1.)
           end

           return (m, )
       end;

julia> model_works = demo_works(xs);

julia> chain_works = sample(model_works, NUTS(0.65), 100);
┌ Info: Found initial step size
└   ϵ = 1.6

julia> var_info = VarInfo(model_works);

julia> spl = SampleFromPrior();

julia> θ_0 = var_info[spl]
2-element Array{Float64,1}:
 -0.38315867392034214
  1.2157641175253535

julia> res_0 = model_works(var_info, spl)
([-0.38315867392034214, 1.2157641175253535],)

julia> DynamicPPL.setval!(var_info, chain_works, 1, 1);

julia> θ_1 = var_info[spl] # <= note that the value has changed since `θ_0`
2-element Array{Float64,1}:
 -0.5500762603588643
 -0.8341982280432694

julia> res_1 = model_works(var_info, spl) # <= has indeed changed since `res_0`
([-0.5500762603588643, -0.8341982280432694],)
 ...

So the in first example setval! fails.

[torfjelde]

Seems like this is the offending line: https://github.com/TuringLang/DynamicPPL.jl/blob/master/src/varinfo.jl#L1183..L1183

When ran on the failing example, indices is empty.

[torfjelde]

Uhhh:

julia> regex = r"^m[1]$|^m[1]\["
r"^m[1]$|^m[1]\["

julia> match(regex, "m[1]") === nothing
true

[torfjelde]

Crap, of course:

julia> regex = r"m\[1\]$|m\[1\]\["
r"m\[1\]$|m\[1\]\["

julia> match(regex, "m[1]")
RegexMatch("m[1]")

So we need to escape the names!

[devmotion]

You have to escape [ and ] by writing

julia> regex = r"^m\[1\]$|^m\[1\]\["

[torfjelde]

Lol @devmotion , you didn't get that until NOW? #5secondsfaster

[devmotion]

Could we maybe use subsumes instead of reimplementing this logic with regex matching?

[torfjelde]

We don't have VarName for keys though, right?

[devmotion]

No I realized that it's probably not useful, exactly due to this issue.

[torfjelde]

Immediate solution:

function regex_escape(s::AbstractString)
    res = replace(s, r"([()[\]{}?*+\-|^\$\\.&~#\s=!<>|:])" => s"\\\1")
    replace(res, "\0" => "\\0")
end

from JuliaLang/julia#29643

But you're right though, Regex isn't the nicest way to deal with this stuff...

[torfjelde]

But it does fix the issue:

julia> using DynamicPPL, Turing
[ Info: Precompiling DynamicPPL [366bfd00-2699-11ea-058f-f148b4cae6d8]
[ Info: Precompiling Turing [fce5fe82-541a-59a6-adf8-730c64b5f9a0]

julia> Turing.turnprogress(false)
[ Info: [Turing]: progress logging is disabled globally
[ Info: [AdvancedVI]: global PROGRESS is set as false
false

julia> @model function demo(xs, ::Type{TV} = Vector{Float64}) where {TV}
           m = TV(undef, 2)
           for i in 1:2
               m[i] ~ Normal(0, 1)
           end

           for i in eachindex(xs)
               xs[i] ~ Normal(m[1], 1.)
           end

           return (m, )
       end
demo (generic function with 2 methods)

julia> xs = randn(3);

julia> model = demo(xs);

julia> chain = sample(model, NUTS(0.65), 100);
┌ Info: Found initial step size
└   ϵ = 1.6

julia> generated_quantities(model, chain)
50×1 Array{Tuple{Array{Float64,1}},2}:
 ([-0.6466888684208906, -1.0605924818561454],)
 ([-0.6466888684208906, -1.0605924818561454],)
 ([-0.21895508638907632, 1.6653331143718089],)
 ([-0.21895508638907632, 1.6653331143718089],)
 ([-0.2997309317443484, -0.029323999401321466],)
 ([-1.0387336145893835, 0.7184211285862931],)
 ([-0.21765620075312997, 0.01436077650117068],)
 ([0.529802098448724, -0.2980663360869661],)
 ([0.11811237219422727, -0.5270924388346214],)
 ([-1.0033004645889954, 1.0369564237981046],)
 ([-0.6387891971861386, 0.6617567920524946],)
 ([-0.010075207468817182, 0.38321779739786466],)
 ...

[torfjelde]

Should I just make a PR with this solution? Seems like this is something that ought to be fixed asap...

[torfjelde]

Will also add some tests, so this doesn't happen in the future

[devmotion]

Maybe it would be safer to use

string_vn = string(vn)
string_vn_indexing = string_vn * "["
findall(keys) do x
    string_x = string(x)
    return string_x == string_vn || startswith(string_x, string_vn_indexing)
end

[torfjelde]

Nice, that indeed seems safer 👍

[devmotion]

Fixed by #168.