CODEWITHSUNDEEP
r
temor
temor

Reputation: 1029

How to add the index from list using cbind?

My data looks like :

lis=list(NULL, NULL, structure(c("A", "30", "5"), .Dim = c(3L, 1L), .Dimnames = list(
         c("Name", "M", "E") , "foo")), structure(c("B", "19", 
         "9"), .Dim = c(3L, 1L), .Dimnames = list(c("Name", "M", "E"), "foo")))

Combine :

dat=do.call(cbind, lis)

Here I want to replace foo with the real correspondence (index from lis)

desired output :

       3      4 
 Name "A"  "B" 
 M    "30" "19"
 E    "5"  "9"

Upvotes: 2

Views: 520

Answers (2)

James
James

Reputation: 66844

If I understand correctly you would like the label the columns of dat to match how lis in indexed. However, lis has no names, just an automatic numbering that appears in output. You can simulate this using seq_along and filtering out the NULL elements:

colnames(dat) <- seq_along(lis)[!sapply(lis,is.null)]
dat
     3    4   
Name "A"  "B" 
M    "30" "19"
E    "5"  "9"

If lis did have names you can use names(lis) instead of the seq_along.

Upvotes: 2

Maurits Evers
Maurits Evers

Reputation: 50678

You can do

as.data.frame(Filter(Negate(is.null), lis))
#     foo foo.1
#Name   A     B
#M     30    19
#E      5     9

Explanation: Filter(Negate(is.null), lis) removes NULL entries from your list prior to converting entries to a data.frame.

To replace column names with the index of the list entry do

setNames(
    data.frame(Filter(Negate(is.null), lis)), 
    which(sapply(lis, function(x) !is.null(x))))
#      3  4
#Name  A  B
#M    30 19
#E     5  9

Upvotes: 2

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