从 R 中的数据框列表中删除特定数据框

Question

I have read and used the answers to the following question ( Remove specific data frame from a list of data frames in R ), where one specific data frame was to be removed from a list. I now need to build on this but am struggling to find the right solution. I have a list of 48 data frames and would like to remove several items from the list, is there a similar code I can use?

Using the same example as the similar question, if to remove $d2 is my.list = my.list[-2] , how would I remove $d2, $d3 and $d6 - ideally at the same time, or one at a time?

Writing the same code consecutively doesn't appear to work, eg.

my.list = my.list[-2]
my.list = my.list[-3] #or should this be [-2] as [3] has become [2] when i removed the original [2]
my.list = my.list[-6] #same again



my.list
$d1
  y1 y2
1  1  4
2  2  5
3  3  6

$d2
  y1 y2
1  3  6
2  2  5
3  1  4

$d3
  y1 y2
1  1  4
2  2  5
3  3  6

$d4
  y1 y2
1  3  6
2  2  5
3  1  4

$d5
  y1 y2
1  1  4
2  2  5
3  3  6

$d6
  y1 y2
1  3  6
2  2  5
3  1  4

Answer 1

There are a variety of valid answers in the comments using numeric indices. Here's yet another:

my.list2 <- my.list[ !    #negation operator
                         names(my.list) %in% c('d2','d3','d6') ]  #logical index
#check
> my.list2
$d1
  y1 y2
1  1  4
2  2  5
3  3  6

$d4
  y1 y2
1  3  6
2  2  5
3  1  4

$d5
  y1 y2
1  1  4
2  2  5
3  3  6

The reason your attempt failed is that the sequence of values in my.list changed as soon as you removed the first item. Notice that I assigned to a different named item. That's a much safer strategy.

The reason I added a demonstration of a logical indexing scheme is its superior generality. You can instead define a criterion that you might use on each item in turn using sapply . The logical vector that results can be used as a selection vector.

Example for testing:

dput(my.list)
list(d1 = structure(list(y1 = 1:3, y2 = 4:6), class = "data.frame", row.names = c("1", 
"2", "3")), d2 = structure(list(y1 = 3:1, y2 = 6:4), class = "data.frame", row.names = c("1", 
"2", "3")), d3 = structure(list(y1 = 1:3, y2 = 4:6), class = "data.frame", row.names = c("1", 
"2", "3")), d4 = structure(list(y1 = 3:1, y2 = 6:4), class = "data.frame", row.names = c("1", 
"2", "3")), d5 = structure(list(y1 = 1:3, y2 = 4:6), class = "data.frame", row.names = c("1", 
"2", "3")), d6 = structure(list(y1 = 3:1, y2 = 6:4), class = "data.frame", row.names = c("1", 
"2", "3")))