[R] use value in variable to be name of another variable

Jim Lemon drjimlemon at gmail.com
Mon Jul 11 23:59:04 CEST 2016


Hi Matthew,
This question is a bit mysterious as we don't know what the object
"chr" is. However, have a look at this and see if it is close to what
you want to do.

# set up a little matrix of character values
tTargTFS<-matrix(paste("A",rep(1:4,each=4),"B",rep(1:4,4),sep=""),ncol=4)
# try the assignment on the first row and column
assign(tTargTFS[1,1],tTargTFS[-1,1])
# see what it looks like - okay
A1B1
# run the assignment over the matrix
for(i in 1:4) assign(tTargTFS[1,i],tTargTFS[-1,i])
# see what the variables look like
A1B1
A2B1
A3B1
A4B1

It does what I would expect.

Jim


On Tue, Jul 12, 2016 at 6:01 AM, Matthew
<mccormack at molbio.mgh.harvard.edu> wrote:
> I want to get a value that has been assigned to a variable, and then use
> that value to be the name of a variable.
>
> For example,
>
> tTargTFS[1,1]
> # returns:
>                 V1
> "AT1G01010"
>
> Now, I want to make AT1G01010 the name of a variable:
> AT1G01010 <- tTargTFS[-1,1]
>
> Then, go to the next tTargTFS[1,2]. Which produces
>                V1
> "AT1G01030"
> And then,
> AT1G01030 <- tTargTFS[-1,2]
>
> I want to do this up to tTargTFS[1, 2666], so I want to do this in a script
> and not manually.
> tTargTFS is a list of 2: chr [1:265, 1:2666], but I also have the data in a
> data frame of 265 observations of 2666 variables, if this data structure
> makes things easier.
>
> My initial attempts are not working. Starting with a test data structure
> that is a little simpler I have tried:
> for (i in 1:4)
> { ATG <- tTargTFS[1, i]
> assign(cat(ATG), tTargTFS[-1, i]) }
>
> Matthew
>
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