Creates a single data rule

Usage

rule(expr, name = NA, allow_na = FALSE, negate = FALSE, ...)

# S3 method for class 'rule'
print(x, ...)

Arguments

expr: an expression which dictates which determines when a rule is good. Note that the expression is evaluated in check_data(), within the given framework. That means, for example if a the data given to check_data() is an arrow dataset, the expression must be mappable from arrow (see also arrow documentation). The expression can be given as a string as well.
name: an optional name for the rule for reference
allow_na: does the rule allow for NA values in the data? default value is FALSE. Note that when NAs are introduced in the expression, allow_na has no effect. Eg when the rule as.numeric(vs) %in% c(0, 1) finds the values of vs as c("1", "A"), the rule will throw a fail regardless of the value of allow_na as the NA is introduced in the expression and is not found in the original data. However, when the values of vs are c("1", NA), allow_na will have an effect.
negate: is the rule negated, only applies to the expression not allow_na, that is, if expr = mpg > 10, allow_na = TRUE, and negate = TRUE, it would match all mpg <= 10 as well as NAs.
...: additional arguments that are carried along for your documentation, but are not used. Could be for example date, person, contact, comment, etc
x: a rule to print

Value

The rule values as a list

Methods (by generic)

print(rule): Prints a rule

Examples

r <- rule(mpg > 10)
r
#> <Verification Rule>
#>   expr: 'mpg > 10'
#>   name: 'Rule for: mpg'
#>   allow NA: FALSE
#>   negated:  FALSE

r2 <- rule(mpg > 10, name = "check that mpg is reasonable", allow_na = TRUE,
           negate = FALSE, author = "me", date = Sys.Date())
r2
#> <Verification Rule>
#>   expr: 'mpg > 10'
#>   name: 'check that mpg is reasonable'
#>   allow NA: TRUE
#>   negated:  FALSE
#>   author: 'me'
#>   date: '2026-04-10'

check_data(mtcars, r)
#>    check_type          name     expr allow_na negate tests  pass  fail   warn
#>        <char>        <char>   <char>   <lgcl> <lgcl> <int> <int> <int> <char>
#> 1:   row_rule Rule for: mpg mpg > 10    FALSE  FALSE    32    32     0       
#>     error              time
#>    <char>        <difftime>
#> 1:        0.0004093647 secs

rs <- ruleset(
  rule(mpg > 10),
  rule(cyl %in% c(4, 6)), # missing 8
  rule(qsec >= 14.5 & qsec <= 22.9)
)
rs
#> <Verification Ruleset with 3 elements>
#>   [1] 'Rule for: mpg' matching `mpg > 10` (allow_na: FALSE)
#>   [2] 'Rule for: cyl' matching `cyl %in% c(4, 6)` (allow_na: FALSE)
#>   [3] 'Rule for: qsec' matching `qsec >= 14.5 & qsec <= 22.9` (allow_na: FALSE)
check_data(mtcars, rs)
#>    check_type           name                        expr allow_na negate tests
#>        <char>         <char>                      <char>   <lgcl> <lgcl> <int>
#> 1:   row_rule  Rule for: mpg                    mpg > 10    FALSE  FALSE    32
#> 2:   row_rule  Rule for: cyl            cyl %in% c(4, 6)    FALSE  FALSE    32
#> 3:   row_rule Rule for: qsec qsec >= 14.5 & qsec <= 22.9    FALSE  FALSE    32
#>     pass  fail   warn  error              time
#>    <int> <int> <char> <char>        <difftime>
#> 1:    32     0               0.0003030300 secs
#> 2:    18    14               0.0010342598 secs
#> 3:    32     0               0.0003006458 secs