Evaluate MULTIPLE equations writern in a character/string vector in R-CodePudding

As many of you have suggested, to evaluate an equation writing in a string or character, one can use eval(parse(text = "your equation")) as follows:

"1 1"
eval(parse(text = "1 1"))
2

This works very well when you have only one equation. But when you have a vector of equations written as strings/characters, it only evaluates the last equation:

eval(parse(text = c("1 1","2 2","3 3")))
6

How could one evaluate all these expressions and have the vector of results at the end?

c(2,4,6)

CodePudding user response：

It is not vectorized, i.e. it needs to be looped

unname(sapply(c("1 1","2 2","3 3"), function(x) eval(parse(text = x))))
[1] 2 4 6

If we know the operator, an option is also to either split up or use read.table to read as two columns and then use rowSums

rowSums(read.table(text = c("1 1","2 2","3 3"), header = FALSE, sep = " "))
[1] 2 4 6

CodePudding user response：

Purrr is your friend.

library(purrr)

equations <- c("1 1","2 2","3 3")

map_dbl(.x = equations, .f = function(equation){
  
  eval(parse(text = equation))
})

[1] 2 4 6