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Retrieve the subset expression from a split value

Source: R/tree_accessors.R
value_expr.Rd

Returns the subsetting expression associated with a SplitValue (or ValueWrapper) object, or NULL for objects without one. This expression is used internally to subset data when tabulating.

Usage 

value_expr(obj)

# S4 method for class 'ValueWrapper'
value_expr(obj)

# S4 method for class 'ANY'
value_expr(obj)

Arguments

obj

(ValueWrapper or ANY)
a split value object, typically a SplitValue constructed by SplitValue(). Any other object returns NULL.

Value

An expression object, or NULL.

Examples 

sv <- SplitValue("A", sub_expr = expression(ARM == "A"))
value_expr(sv)
#> expression(ARM == "A")

value_expr("not a SplitValue") # NULL
#> NULL