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Create a scidb.expression by parsing an R expression

Source: R/afl.R
expression_parser.Rd

This recursive methods creates a tree of scidb.expression objects corresponding to the R expression supplied as a parameter.

R variables can be interpolated into the expression by prepending them with the double-exclamation !! operator.

In addition to base R unary and binary operands, this method treats several operations as special cases, and also defines several custom operations of its own that can be used:

  • %in%: this vector membership operator, e.g. x %in% c(1,2,...), can only be used when the RHS value is a non-symbolic scalar or vector value

  • %not_in%: this custom operand is the negation of %in%

  • %like%, %contains%, %starts_with%, and %ends_with%: these custom operands are treated as special cases of the regex function stringr::str_detect, and can be applied to symbolic and non-symbolic arguments

Usage

expression_parser(...)

Arguments

...

R expression to parse

Value

scidb.expression object