Construct a set of priors — priors • tidyabc

abc_prior S3 objects are used to hold the specification of prior and intermediate proposal distributions. They are inputs to the main abc_...() workflow functions.

Usage

priors(...)

Arguments

...: a list of formulae. Two sided will be interpreted as distribution or derived value specifications. One sided as constraints between parameters. A distribution is specified as the name of the family of statistical distributions and their parameters: e.g.: x ~ norm(mean=3,sd=2). The name will be matched to the first hit on the search path.

Value

an S3 object of class abc_prior which contains

a list of dist_fns
a cor attribute describing their correlation
a derived attribute describing derive values
a constraints attribute listing the constraints
a params attribute listing the names of the parameters

Examples

p = priors(
  mean ~ tidyabc::rgamma2(4,2),
  sd ~ gamma2(2,1),
  shape ~ mean^2 / sd^2,
  rate ~ mean / sd^2,
  ~ mean > sd
)

print(p)
#> Parameters: 
#> * mean: gamma2(mean = 4, sd = 2)
#> * sd: gamma2(mean = 2, sd = 1)
#> Constraints:
#> * mean > sd
#> Derived values:
#> * shape = mean^2/sd^2
#> * rate = mean/sd^2

# Plot methods are also provided:
if (interactive()) plot(p)

# constraints:
p@constraints
#> [[1]]
#> ~mean > sd
#> <environment: 0x55e4aa6b75b8>
#>