R - Reading vector or dataframe from string

Question

I would like to read a data frame from a string. It is a bit difficult to explain, and, so far I couldn't find the answer anywhere.

Let's imagine I have several data frames: "Param1", "Param2", ... "Param100". I would like to be able to access them from a for loop:

for (i in c(1:100)){
  a <- paste0("Param",i)
  b <- ??? (a)
}

Where b would become "Param1", ... "Param100" when i varies from 1 to 100.

See http://stackoverflow.com/questions/9057006/getting-strings-recognized-as-variable-names-in-r — Philippe Marchand, Aug 05 '15 at 10:24

score 2 · Accepted Answer · answered Aug 05 '15 at 10:25

2

Use get.

for (i in 1:100) {
  b <- get(paste0("Param", i))
}

answered Aug 05 '15 at 10:25

Josh

1

Cant you just use `mget` without a loop? – David Arenburg Aug 05 '15 at 11:57
Yes, you could. `mget(paste0("Param", 1:100))` I believe would work. You'll end up with a list to operate on. – Josh Aug 05 '15 at 14:40
More like `mget(ls(pattern = paste0("Param", 1:100)))` – David Arenburg Aug 05 '15 at 14:41
Oops, thanks David. I've fixed my comment of a bug. Its a bit easier than your suggestion though, the `ls` part isn't necessary I think. – Josh Aug 05 '15 at 14:43
I think it is necessary. – David Arenburg Aug 05 '15 at 14:43
Oh, right because there is no regex involved. It would be necessary for more general lookups. – David Arenburg Aug 05 '15 at 14:46

1 Answers1