Extended generated_quantities function (#299)

Extended `generated_quantities` function to also accept a named tuple or keys+values

Co-authored-by: Tor Erlend Fjelde <[email protected]>
Co-authored-by: Hong Ge <[email protected]>

Author: 3 people

src/model.jl

@@ -590,3 +590,50 @@ function generated_quantities(model::Model, chain::AbstractChains)
         model(varinfo)
     end
 end
+
+"""
+    generated_quantities(model::Model, parameters::NamedTuple)
+    generated_quantities(model::Model, values, keys)
+    generated_quantities(model::Model, values, keys)
+
+Execute `model` with variables `keys` set to `values` and return the values returned by the `model`.
+
+If a `NamedTuple` is given, `keys=keys(parameters)` and `values=values(parameters)`.
+
+# Example
+```jldoctest
+julia> using DynamicPPL, Distributions
+
+julia> @model function demo(xs)
+           s ~ InverseGamma(2, 3)
+           m_shifted ~ Normal(10, √s)
+           m = m_shifted - 10
+           for i in eachindex(xs)
+               xs[i] ~ Normal(m, √s)
+           end
+           return (m, )
+       end
+demo (generic function with 1 method)
+
+julia> model = demo(randn(10));
+
+julia> parameters = (; s = 1.0, m_shifted=10);
+
+julia> generated_quantities(model, parameters)
+(0.0,)
+
+julia> generated_quantities(model, values(parameters), keys(parameters))
+(0.0,)
+```
+"""
+function generated_quantities(model::Model, parameters::NamedTuple)
+    varinfo = VarInfo(model)
+    setval_and_resample!(varinfo, values(parameters), keys(parameters))
+    return model(varinfo)
+end
+
+function generated_quantities(model::Model, values, keys)
+    varinfo = VarInfo(model)
+    setval_and_resample!(varinfo, values, keys)
+    return model(varinfo)
+end