R + Data frame name as string variable

Question

I have a list of data frames, and I'm looking to assign to each data frame within the list a variable column that is simple a character vector of the given dataframe's name.

data <- list(
    d1 = data.frame(animal = sample(c("cat","dog","bird"), 5, replace = T)),
    d2 = data.frame(animal = sample(c("cat","dog","bird"), 5, replace = T)),
    d3 = data.frame(animal = sample(c("cat","dog","bird"), 5, replace = T))
)

This yields:

> data 
$d1
  animal
1    cat
2   bird
3    cat
4    cat
5    cat

$d2
  animal
1    dog
2    cat
3    cat
4    cat
5   bird

$d3
  animal
1    cat
2    dog
3    cat
4    cat
5    cat

What I want to do is create something like the following:

> newdata 
$d1
  animal newvar
1    cat     d1
2    cat     d1
3    cat     d1
4    dog     d1
5    cat     d1

$d2
  animal newvar
1   bird     d2
2    cat     d2
3   bird     d2
4    cat     d2
5    cat     d2

$d3
  animal newvar
1   bird     d3
2   bird     d3
3    cat     d3
4    cat     d3
5   bird     d3

But I can't quite figure out how to actually reference the data frame name --in a list of data frames-- and turn it into a character vector appropriately.

Something like the following does not work:

namefunc <- function(x) {
    x <- x %>% transform(newvar = as.character(x))
}

newdata <- namefunc(data)

akrun · Accepted Answer · 2016-01-20 19:08:47Z

4

We can use Map to cbind the corresponding list elements of 'data' with the names of 'data'

Map(cbind, data, newvar= names(data))

answered Jan 20, 2016 at 19:08

akrun

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Comments

jogo · Accepted Answer · 2016-01-20 19:20:46Z

1

lapply(names(data), function(d) transform(data[[d]], newvar=d))

or eventually:

L <- lapply(names(data), function(d) transform(data[[d]], newvar=d))
names(L) <- names(data)

answered Jan 20, 2016 at 19:20

jogo

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