Creating dataframe names on the fly?

I am aware that it is easily possible to create var names on the fly. e.g.
assign(paste("m",i,sep=""),j)
but is it possible to assign dataframes to variables created on the fly?

e.g.
If I have a dataframe called master and I wanted to subset parts of those
data into separate dataframes, I could do:

m1=subset(master,master$SAMPLE=='1')
m2=subset(master,master$SAMPLE=='2')
.....

but I would like to do this in a loop. Can someone give me suggestions on
how to accomplish this?


I tried assign(paste("m",i,sep=""),subset(master,master$SAMPLE==i) with no
success.

Are you sure you really need to name these dataframes?

Here's a workaround that I use for these cases.  Create your new data
frames and add them to a list, as in

myframes <- list(subset(master,master$SAMPLE=='1'),
m2=subset(master,master$SAMPLE=='2'))

Then when you want to use these things,  you can get the first one as
myframes[[1]]
or myframes[[2]].

You can name the objects inside the list:

names(myframes) <- c("A","B")

This is just as good as referring to them  by name, in my experience.
It also has the benefit that because your dataframes are in a list,
then you can use features like lapply to do things for each dataset.

I'm reading ?assign now, and it appears  you can actually name these things.

name <- paste("fred",4,sep="")
x <- data.frame(py=rnorm(10))
assign(name,x)
ls()

[1] "fred4" "mname" "name"  "x"

name

[1] "fred4"

fred4

py
1  -1.04243477
2  -0.66475049
3  -0.08576428
4   0.64369356
5  -0.06828696
6   1.15710627
7  -2.45041700
8   0.40139655
9   0.27320936
10 -0.98028020

pj

Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas