use name of dataframe on a list of dataframes

Question

I try to solve a problem from a question I have previously posted looping inside list in r

Is there a way to get the name of a dataframe that is on a list of dataframes? I have listed a serie of dataframes and to each dataframe I want to apply myfunction. But I do not know how to get the name of each dataframe in order to use it on nameofprocesseddf of myfunction.

Here is the way I get the list of my dataframes and the code I got until now. Any suggestion how I can make this work?

library(missForest)
library(dplyr)

myfunction <- function (originaldf, proceseddf, nonproceseddf, nameofprocesseddf=character){
NRMSE <- nrmse(proceseddf, nonproceseddf, originaldf)
comment(nameofprocesseddf) <- nameofprocesseddf
results <- as.data.frame(list(comment(nameofprocesseddf), NRMSE))
names(results) <- c("Dataset", "NRMSE")
return(results)
}
a <- data.frame(value = rnorm(100), cat = c(rep(1,50), rep(2,50)))
da1 <- data.frame(value = rnorm(100,4), cat2 = c(rep(2,50), rep(3,50)))

dataframes <- dir(pattern = ".txt") 
list_dataframes <- llply(dataframes, read.table, header = T, dec=".", sep=",")
n <- length(dataframes)

# Here is where I do not know how to get the name of the `i` dataframe 
for (i in 1:n){
modified_list <- llply(list_dataframes, myfunction, originaldf = a, nonproceseddf = da1, proceseddf = list_dataframes[i], nameof processeddf= names(list_dataframes[i]))
write.table(file = sprintf("myfile/%s_NRMSE20%02d.txt", dataframes[i]), modified_list[[i]], row.names = F, sep=",")
}

try names(list_dataframes)[i] -- but where is the name being assigned? — Edward R. Mazurek
– Edward R. Mazurek, Commented Jun 14, 2016 at 13:51
that is exactly my problem I do not know how to assign the name of each dataframe contained on the list. Any idea how I can assign it? — mina
– mina, Commented Jun 14, 2016 at 13:54
llply comes from plyr, not dplyr. I think you will find that your object names are more trouble than they're worth. (I am referring to nonproceseddf, which contains a spelling error, et al, not the content of the question. Shorter names are generally better.) — Frank
– Frank, Commented Jun 14, 2016 at 15:52

G. Lombardo · Accepted Answer · 2016-06-14 15:49:30Z

1

as a matter of fact, the name of a data frame is not an attribute of the data frame. It's just an expression used to call the object. Hence the name of the data frame is indeed 'list_dataframes[i]'.

Since I assume you want to name your data frame as the text file is named without the extension, I propose you use something like (it require the library stringr) :

nameofprocesseddf = substr(dataframes[i],start = 1,stop = str_length(dataframes[i])-4)

answered Jun 14, 2016 at 15:49

G. Lombardo

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2 Comments

Frank Over a year ago

Is there an advantage to stringr::str_length over nchar here?

G. Lombardo Over a year ago

@Frank not really on normal string. but on some UTF-8 string, it might be different. nchar

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