r - Delete a column in a data frame within a list

Question

I made a list out of my dataframe, based on the factor levels in column A. In the list I would like to remove that column. My head is saying lapply, but not anything else :P

$A
ID Test
A   1
A   1

$B
 ID Test
 B   1
 B   3
 B   5

Into this

$A
Test
 1
 1

$B
Test
 1
 3
 5

Answer 1

Assuming your list is called myList, something like this should work:

lapply(myList, function(x) { x["ID"] <- NULL; x })

Update

For a more general solution, you can also use something like this:

# Sample data
myList <- list(A = data.frame(ID = c("A", "A"), 
                              Test = c(1, 1), 
                              Value = 1:2), 
               B = data.frame(ID = c("B", "B", "B"), 
                              Test = c(1, 3, 5), 
                              Value = 1:3))
# Keep just the "ID" and "Value" columns
lapply(myList, function(x) x[(names(x) %in% c("ID", "Value"))])
# Drop the "ID" and "Value" columns
lapply(myList, function(x) x[!(names(x) %in% c("ID", "Value"))])