CODEWITHSUNDEEP
r
Barnaby
Barnaby

Reputation: 1480

Extract elements from the name of an object

I have an object name 

Test12<-c(8,7,4,3,5,67,3,9,6,6,56,742,23,12,45,56)

I would like to extract the last two numbers from the objects name or from Test12 to obtain the numbers 1 and 2 separatedly and place them into two objects. 

a<- 1
b<- 2

I have tried with 

x <- name(Test12)

substrRight <- function(x, n){
substr(x, nchar(x)-n+1, nchar(x))
}
substrRight(x, 2)
[1] "8"  "7"  "4"  "3"  "5"  "67" "3"  "9"  "6"  "6"  "56" "42" "23" "12" "45" "56"

However I get the last 2 ítems of each of the objects elements.

Any help welcomed

Upvotes: 2

Views: 188

Answers (3)

akrun
akrun

Reputation: 887891

You may also try 

 library(stringr)
 list2env(setNames(
        as.list(str_extract_all(deparse(substitute(Test12)),
                        perl("\\d(?=\\b$)|\\d(?=[0-9]$)"))[[1]]),
                       letters[1:2]),
                              envir=.GlobalEnv)

   a
  #[1] "1"
    b
  #[1] "2"

Explanation

 deparse(substitute(Test12)) #gets the name of the object
 #[1] "Test12"

Regex "\\d(?=\\b$) match a digit lookahead for word boundary at the end of string | or \\d(?=[0-9]$)") a digit and lookahead for another digit at the end of string.

Suppose your string is:

 T95es34t12 <- 1:5
  str_extract_all(deparse(substitute(T95es34t12)),  perl("\\d(?=\\b$)|\\d(?=[0-9]$)"))[[1]]
 #[1] "1" "2"

as.list creates a list,then name the elements of list with a, b using setNames and use list2env to assign the name of the list elements to the list values.

Upvotes: 1

Al.Sal
Al.Sal

Reputation: 984

You can use this: 

substrRight <- function(x, n){
    substr(x, nchar(x)-n+1, nchar(x))
}

var.name <- deparse(substitute(test12))
var.nums <- substrRight(var.name, 2) 
var.nums <- strsplit(var.nums, "")
var.nums <- unlist(var.nums)
var.nums <- as.vector(as.numeric(var.nums))

Upvotes: 1

Jota
Jota

Reputation: 17621

nm <- bquote(Test12) or
nm <- quote(Test12) or
nm <- "Test12" or
nm <- deparse(substitute(Test12)) as per answer of @Al.Sal

Will work, then:

a <- substr(nm, nchar(nm)-1, nchar(nm)-1)
b <- substr(nm, nchar(nm), nchar(nm))
> a
[1] "1"
> b
[1] "2"

Upvotes: 1

Related Questions