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Build an extraction schema

Source: R/extract-fields.R
gr_fields.Rd

A goal, expressed as the fields you want filled. Each argument is either a description (a string field) or a gr_field().

Usage

gr_fields(...)

Arguments

...

Named fields. A bare string is shorthand for gr_field(string, type = "string").

Value

A gr_fields object.

Naming the fields

The names become column names, so keep them short and syntactic. The descriptions carry the instruction, and they are worth writing carefully: most extraction disagreements come from an ambiguous field description rather than from the model.

See also

gr_field(), gr_extract(), gr_protocol()

Examples

fields <- gr_fields(
  design  = "The study design, e.g. randomised controlled trial, cohort, case series",
  n       = gr_field("Number of participants randomised, not the number analysed",
                     type = "integer"),
  outcome = gr_field("Direction of the primary result",
                     type = "enum", values = c("positive", "null", "mixed")),
  funded  = gr_field("Whether industry funding is declared", type = "boolean")
)
fields
#> <gr_fields> 4 field(s)
#>   design         string    The study design, e.g. randomised controlled trial, cohort, 
#>   n              integer   Number of participants randomised, not the number analysed
#>   outcome        enum      Direction of the primary result
#>   funded         boolean   Whether industry funding is declared
names(fields)
#> [1] "design"  "n"       "outcome" "funded"