R Language Expression: parse + eval Execute code in string format


Example

In this exemple, we want to execute code which is stored in a string format.

# the string
str <- "1+1"

# A string is not an expression.
is.expression(str)
[1] FALSE

eval(str)
[1] "1+1"

# parse convert string into expressions
parsed.str <- parse(text="1+1")

is.expression(parsed.str)
[1] TRUE

eval(parsed.str)
[1] 2