Keep row names when using rbind.fill in R

Question

Does anyone know how to keep rownames in the rbind.fill function.

library(plyr)

#creating data
a <- mtcars[ 1:5 , c("mpg","hp","gear") ]
b <- mtcars[ 6:10 , c("mpg","disp","gear") ]

#does not work because there are different colnames
rbind(a,b)

#works but eliminates the rownames
bound <- rbind.fill( a , b )

I am setting up a loop where objects will be connected using rbind.fill. Right now I am using the combine function like this:

namess <- c( rownames(a) , rownames(b) )
rownames(bound) <- namess

I thought that there might be a better way. Thanks!

Answer 1

You could try to apply a custom function that performs rbind.fill and sets initial rownames automatically like that:

# List of sample data
ab.list <- list(a <- mtcars[1:5 , c("mpg","hp","gear")], 
                b <- mtcars[6:10 , c("mpg","disp","gear")])

# Apply custom function (rbind and rownames adjustment) to sample data
do.call(function(...) {

  tmp <- plyr::rbind.fill(...)
  rownames(tmp) <- sapply(ab.list, function(i) {
    rownames(i)
  })

  return(tmp)

}, ab.list)

                   mpg  hp gear  disp
Mazda RX4         21.0 110    4    NA
Mazda RX4 Wag     21.0 110    4    NA
Datsun 710        22.8  93    4    NA
Hornet 4 Drive    21.4 110    3    NA
Hornet Sportabout 18.7 175    3    NA
Valiant           18.1  NA    3 225.0
Duster 360        14.3  NA    3 360.0
Merc 240D         24.4  NA    4 146.7
Merc 230          22.8  NA    4 140.8
Merc 280          19.2  NA    4 167.6

Check out this previous post that deals with a similar problem.

Answer 2

Since I posted this question five years ago - a new function became available. smartbind solves this issue.

library( gtools) 

#creating data
a <- mtcars[ 1:5 , c("mpg","hp","gear") ]
b <- mtcars[ 6:10 , c("mpg","disp","gear") ]

smartbind( a , b )