Combing a list of unequal data.frames

Question

I\'m trying to combine a list of unequal data.frames; the obvious do.call(rbind, df.lst) fails but the real problem is padding it out with NAs.

Answer 1

Try

library(plyr)
ldply(df.lst,data.frame)

  .id a b d  e  f  g
1   A 1 5 2  1  1  1
2   A 2 4 3  1  2  2
3   B 1 3 2 NA NA NA
4   B 2 2 3 NA NA NA
5   C 1 4 1  1 NA NA
6   C 2 3 2  3 NA NA

If needed you can remove the first column :

df<-ldply(df.lst,data.frame)
df[,-1]

a b d  e  f  g
1 1 5 2  1  1  1
2 2 4 3  1  2  2
3 1 3 2 NA NA NA
4 2 2 3 NA NA NA
5 1 4 1  1 NA NA
6 2 3 2  3 NA NA

Answer 2

If you want to stick with base R, you can do something like this:

### Get all the columns names
col <- unique(unlist(sapply(df.lst, names)))
col
## [1] "a" "b" "d" "e" "f" "g"

### Fill the missing columns with NA
df.lst <- lapply(df.lst, function(df) {
  df[, setdiff(col, names(df))] <- NA
  df
})

### Then Bind it
do.call(rbind, df.lst)
##     a b d  e  f  g
## A.1 1 5 2  1  1  1
## A.2 2 4 3  1  2  2
## B.1 1 3 2 NA NA NA
## B.2 2 2 3 NA NA NA
## C.1 1 4 1  1 NA NA
## C.2 2 3 2  3 NA NA

Answer 3

We can use

library(dplyr)
bind_rows(df.lst)

Or

library(data.table)
rbindlist(df.lst, fill=TRUE)