Convert string to a variable name

Question

assign is what you are looking for.

assign("x", 5)

x
[1] 5

but buyer beware.

See R FAQ 7.21 http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-can-I-turn-a-string-into-a-variable_003f

You can use do.call:

 do.call("<-",list(parameter_name, parameter_value))

There is another simple solution found there: http://www.r-bloggers.com/converting-a-string-to-a-variable-name-on-the-fly-and-vice-versa-in-r/

To convert a string to a variable:

x <- 42
eval(parse(text = "x"))
[1] 42

And the opposite:

x <- 42
deparse(substitute(x))
[1] "x"

The function you are looking for is get():

assign ("abc",5)
get("abc")

Confirming that the memory address is identical:

getabc <- get("abc")
pryr::address(abc) == pryr::address(getabc)
# [1] TRUE

Reference: R FAQ 7.21 How can I turn a string into a variable?

Use x=as.name("string"). You can use then use x to refer to the variable with name string.

I don't know, if it answers your question correctly.

strsplit to parse your input and, as Greg mentioned, assign to assign the variables.

original_string <- c("x=123", "y=456")
pairs <- strsplit(original_string, "=")
lapply(pairs, function(x) assign(x[1], as.numeric(x[2]), envir = globalenv()))
ls()

assign is good, but I have not found a function for referring back to the variable you've created in an automated script. (as.name seems to work the opposite way). More experienced coders will doubtless have a better solution, but this solution works and is slightly humorous perhaps, in that it gets R to write code for itself to execute.

Say I have just assigned value 5 to x (var.name <- "x"; assign(var.name, 5)) and I want to change the value to 6. If I am writing a script and don't know in advance what the variable name (var.name) will be (which seems to be the point of the assign function), I can't simply put x <- 6 because var.name might have been "y". So I do:

var.name <- "x"
#some other code...
assign(var.name, 5)
#some more code...

#write a script file (1 line in this case) that works with whatever variable name
write(paste0(var.name, " <- 6"), "tmp.R")
#source that script file
source("tmp.R")
#remove the script file for tidiness
file.remove("tmp.R")

x will be changed to 6, and if the variable name was anything other than "x", that variable will similarly have been changed to 6.