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Combine multiple R expressions into a single composite expression

Source: R/helpers.R
combine_rule_elements.Rd

This function takes a list of R expressions and combines them using a logical operator to create a single composite expression. It is useful for building complete rule paths by combining individual split conditions from tree-based models.

Usage

combine_rule_elements(exprs, operator = "&")

Arguments

exprs

A list of R expressions to combine. Each element must be a language object (expression or symbol). The list can be empty (returns TRUE), contain a single expression (returns unchanged), or multiple expressions (combines with operator).

operator

A character string specifying the logical operator to use:

  • "&" (default): combines expressions with AND logic.

  • "|": combines expressions with OR logic.

Value

An R expression object that combines all input expressions. Returns TRUE for empty list, the single expression for length-1 list, or a nested expression for multiple elements.

Examples

# Basic AND combination
expr1 <- rlang::expr(x > 5)
expr2 <- rlang::expr(y < 10)
combine_rule_elements(list(expr1, expr2))
#> x > 5 & y < 10

# OR operator
combine_rule_elements(list(expr1, expr2), operator = "|")
#> x > 5 | y < 10

# Integration with rect_split_to_expr()
split1 <- list(column = "age", value = 30, operator = ">=")
split2 <- list(column = "income", value = 50000, operator = ">")
exprs <- list(
  rect_split_to_expr(split1),
  rect_split_to_expr(split2)
)
rule <- combine_rule_elements(exprs)

# Evaluate with data
test_data <- data.frame(age = 35, income = 60000)
eval(rule, test_data)
#> [1] TRUE

# Edge cases
combine_rule_elements(list()) # returns TRUE
#> [1] TRUE
combine_rule_elements(list(rlang::expr(x > 0))) # returns x > 0
#> x > 0