[R] assigning a list item using a variable for a name

From: RSVP <paul_at_ptrow.com>
Date: Tue, 22 Mar 2011 16:47:19 -0700 (PDT)

I have a list.

my.list <- list(Tom=c(1,2,3), Dick=c(4,5,6), Harry=c(7,8,9))

I assign one of the names of the list to a variable.

name <- "Harry"

I can access the value of the list using the variable as follows:

 eval(parse(text=paste("my.list$", name, sep="")))

[1] 7 8 9

But how do I change the value of my.list$Harry using the variable name? This doesn't work:

 eval(parse(text=paste("my.list$", name, sep=""))) <- c(1,4,7)

Error in eval(parse(text = paste("my.list$", name, sep = ""))) <- c(1, :   target of assignment expands to non-language object

The following only replaces the first element of my.list$Harry

 my.list[name] <- c(1,4,7)
Warning message:
In my.list[name] <- c(1, 4, 7) :
  number of items to replace is not a multiple of replacement length

> my.list[name]

[1] 1

Any suggestions?


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Received on Wed 23 Mar 2011 - 02:07:54 GMT

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