[R] Using changing names in loop in R

[Joshua Wiley]

On Sat, Nov 6, 2010 at 3:13 PM, Tuatara <franziskabroell at gmail.com> wrote:
>
> A more detailed example:
>
> Say I would like to read in data files that are set-up identically and have
> identical (but somewhat) different text names (see below):
>
> data_1 <- read.csv("data1.txt")
> data_2 <- read.csv("data2.txt")
> data_3 <- read.csv("data3.txt")
>
> How do I automate this process?

Well, the (nearly) verbatim automated duplicate would be:

for(i in 1:3) {
  assign(x = paste("data", i, sep = "_"), value =
read.csv(paste("data", i, ".txt", sep = '')))
}

but the preferred way would be:

dat <- lapply(1:3, function(x) {read.csv(paste("data", x, ".txt", sep = ''))})

which would read in and store all three files in one convenient list.

Josh

>
> (I assume the way I make R understand that the data file extension is to be
> read as a number rather than a string is the same for things like applying
> functions to matrices with different extensions, e.g. data_i, i = 1,2,3)
> --
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>
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/