evalR (version 0.0.1)

eval_text: safely evaluate text

Description

Safe alternative to using eval + parse

Usage

eval_text(
  text,
  singular_operators = NULL,
  binary_operators = NULL,
  valid_functions = NULL,
  map = NULL,
  mapping_names = NULL
)

Value

numeric or logical vector

Arguments

text

the string/code/statement you want to parse.

singular_operators

tokens of length 1 that operate on a right hand value. For example, the `-` token is an operator to negate a vector. NULL value will be replaced with c("-", "!").

binary_operators

tokens of any length that operate on a left and right hand values. For example, the `+` token is an operator that adds a left vector to a right vector. NULL value will be replaced with c(",", "|", "&", "<=", "<", ">=", ">", "==", "!=", "+", "-", "*", "%/%", "/", "%%", "%in%", ":", "^"). The order determines the precedence of the operators.

valid_functions

tokens of any length that are prefixed on a parenthesis block and specify a function to run on the provided parameters within the block. For example, the `log` token will evaluate the logarithm value of the first parameter. Note named parameters are not support. NULL value will be replaced with c("log", "c", "any", "all", "abs", "ifelse").

map

a named list of data.frames/lists/matrices. Where names are keys for referencing the values in the text parameters.

mapping_names

optional argument to make the function faster or limit which map elements can be referenced.

Details

See vignette("Overview", package = "evalR")

Examples

eval_text("1 + 2")

# using the map parameter 
map_obj <- list("#" = data.frame(x = 1:5, y = 5:1),"$" = list(z = -(1:5)))
y <- evalR::eval_text("#x# + $z$", map=map_obj)