Load a design specification from a JSON file

Usage

load_spec(path, validate = TRUE)

Arguments

path: Path to a JSON design-specification file, or the JSON text itself, as the scripts from generate_r_script() and generate_design_analysis() embed it.
validate: Whether to validate the specification after reading it. TRUE (the default) applies validate_spec() with strict = TRUE, and FALSE skips validation. Any other value validates leniently, with strict = FALSE, so that an unknown field draws a warning, not an error.

Value

The specification as a nested list, with sub-lists left unsimplified so that the structure round-trips exactly. Pass the result to simulate_design().

Details

The specification is validated by default, via validate_spec(), because several ways of getting one wrong produce plausible data and no error at all: a mistyped coefficient key resolves to no column and so silently sets that effect to zero, and a response parameter left over from another family is ignored. Validation also refuses a specification declaring a spec_version newer than this implementation understands, and never reads such a file in part.

The file is read as UTF-8, with or without a byte-order mark. A file that repeats a key within one JSON object is refused whatever validate says, because JSON leaves a repeated key undefined and the R and 'Python' readers settle it differently: one coefficient given twice was applied twice at its first value in R and once at its second in 'Python'.

Examples

spec <- build_spec(list(name = "demo", seed = 1, design_kind = "between",
  factor_name = "group", lev1 = "a", lev2 = "b", n_subject = 20,
  intercept = 0, effect = 0.5, family = "gaussian", resp_name = "", sigma = 1))
f <- tempfile(fileext = ".json")
writeLines(spec_json(spec), f)
identical(simulate_design(load_spec(f)), simulate_design(spec))
#> [1] TRUE