For loop to eliminate columns in multiple dfs - r

Question

I've got about 10 dataframes. For the example, here are two:
name <- c("A", "B", "C")
name.footnote <- c("this", "that", "the other")
class <- c("one", "two", "three")
class.footnote <- c("blank", "blank", "blank")
df1 <- data.frame(name, name.footnote, class, class.footnote)
df2 <- data.frame(name, name.footnote, class, class.footnote)
When I eliminate columns from them one at a time, my code works fine.
library(dplyr)
df1 <- select(df1, -ends_with("footnote"))
I'd like to write a loop to process both dfs with less code, but can't get my loop working right. I keep getting the same error message:
Error in UseMethod("select_") : no applicable method for 'select_'
applied to an object of class "character".
See a few of the many loop codes I've tried, below. What am I missing?
listofDfs <- list("df1","df2")
1.
lapply(listofDfs, function(df){
df <- select(df, -ends_with("footnote"))
return(df)
}
)
2.
for (i in listofDfs){
i <- select(i, -ends_with("footnote"))
}

Answer 1

Try dropping the quotes when defining your list listofDfs <- list(df1,df2). As the error states, when you have the quotes the elements of your list are character instead of the data.frame that select() is expecting.
library(dplyr)
listofDfs <- list(df1,df2)
#using lapply
list_out1 <- lapply(listofDfs, function(df){
df <- select(df, -ends_with("footnote"))
return(df)
})
#using for loop
list_out2 <- vector("list", length(listofDfs))
for (i in seq_along(listofDfs)){
list_out2[[i]] <- select(listofDfs[[i]], -ends_with("footnote"))
}
follow up per comment
you can use get and assign to work with your original character list and manipulate the dfs in your global environment while iterating.
listofDfs <- list('df1','df2')
invisible(lapply(listofDfs, function(i){
df <- select(get(i, globalenv()), -ends_with("footnote"))
assign(i, df, envir = globalenv())
}))
for (i in listofDfs){
df <- select(get(i, globalenv()), -ends_with("footnote"))
assign(i, df, envir = globalenv())
}