Validates the output of statistical functions to ensure it
conforms to expected structure. The expected structure includes specific
column names (label, description, qualifiers, value) and at least one row.
This validator is typically used with try_and_validate() to ensure
statistical functions return correctly formatted results.
Value
An error message (character) if validation fails, otherwise NA_character_.
Use with try_and_validate() to automatically handle validation failures.
Examples
library(data.table)
# Valid statistical output - correctly formatted
valid_stats <- data.table(
label = c("N", "n_events", "Rate"),
description = c(
"Number of subjects",
"Number with adverse events",
"Percentage with events"
),
qualifiers = NA_character_,
value = c(250L, 45L, 18.0)
)
# Validation passes
validate_stat_output(valid_stats) # Returns NA_character_
#> [1] NA
# Invalid: wrong class (must be data.table)
invalid_vector <- c(N = 250, events = 45)
validate_stat_output(invalid_vector) # Returns error message
#> [1] "Expected (data.table::data.table). Found: numeric"
# Invalid: missing required columns
incomplete_stats <- data.table(
label = c("N", "Rate"),
value = c(250L, 18.0)
)
validate_stat_output(incomplete_stats) # Shows missing columns
#> [1] "Expected columns: ( description, label, qualifiers, value )\nFound columns: ( label, value )\n\tMissing items in actual: ( description, qualifiers )"
# Invalid: empty result (0 rows)
empty_stats <- data.table(
label = character(),
description = character(),
qualifiers = character(),
value = numeric()
)
validate_stat_output(empty_stats) # Error: 0 rows returned
#> [1] "The statistical function returned a data.table with 0 rows"