R：使字符串引用一个对象

Question

I have a large list of files ( file1 , file2 , file3 , etc.) and, for each analysis, I want to refer to two files from this list (eg function(file1,file2) ). When I try to do this using paste0("file", pairs[1,x] I get back the character string "file1" rather than the object file1 .

How can I refer to the objects rather than create a character string?

Thank you very much!

Additional comment:

• pairs is a 2xn matrix where each column is the combination of files for one analysis (eg pairs[1,1] = 1 and pairs[2,1] = 2 for the comparison between file1 and file2).

Answer 1

How to get the variable from a string containing the variable name:

> a = 10
> string = "a"
> string
[1] "a"
> eval(parse(text = string))
[1] 10
> eval(parse(text = "a"))
[1] 10

Hope this helps.

Answer 2

Are you looking for get() ???

a <- 1:5
> get("a")
[1] 1 2 3 4 5

Answer 3

另一种选择：eval(as.name("file"))。