R devel - May 2006 - bug in rbind.data.frame with factors (PR#8868)

Full_Name: Rafal Kustra
Version: 2.1.1
OS: Linux, MacOS 10.3
Submission from: (NULL) (69.195.47.62)


When Rbinding two data frames with factors, strange result occur (but no error)
when the order of data frame variables is different in two data frames:
> d1=as.data.frame(list(x=1:10,y=letters[1:10]))
> d2=as.data.frame(list(y=LETTERS[1:5],x=7:11))
> d2
  y  x
1 A  7
2 B  8
3 C  9
4 D 10
5 E 11
> rbind(d1,d2)
    x    y
1   1    a
2   2    b
3   3    c
4   4    d
5   5    e
6   6    f
7   7    g
8   8    h
9   9    i
10 10    j
11  7 <NA>
21  8 <NA>
31  9 <NA>
41 10 <NA>
51 11 <NA>
Warning message:
invalid factor level, NAs generated in: "[<-.factor"(`*tmp*`, ri,
value = c("A",
"B", "C", "D", "E")) 


Things work correctly when the order of variables is the same:
> d3=as.data.frame(list(x=7:11,y=LETTERS[1:5]))
> rbind(d1,d3)
    x y
1   1 a
2   2 b
3   3 c
4   4 d
5   5 e
6   6 f
7   7 g
8   8 h
9   9 i
10 10 j
11  7 A
21  8 B
31  9 C
41 10 D
51 11 E
>

How is this a bug? From the help page for cbind/rbind:

Description
Take a sequence of vector, matrix or data frames arguments and
combine by _columns_ or _rows_, respectively.
(emphasis added)

Note that it does _not_ say "combine by variable names".

Peter Ehlers

rafalku at gmail.com wrote:
> Full_Name: Rafal Kustra
> Version: 2.1.1
> OS: Linux, MacOS 10.3
> Submission from: (NULL) (69.195.47.62)
> 
> 
> When Rbinding two data frames with factors, strange result occur (but no
error)
> when the order of data frame variables is different in two data frames:
> 
> 
>>d1=as.data.frame(list(x=1:10,y=letters[1:10]))
>>d2=as.data.frame(list(y=LETTERS[1:5],x=7:11))
>>d2
> 
>   y  x
> 1 A  7
> 2 B  8
> 3 C  9
> 4 D 10
> 5 E 11
> 
>>rbind(d1,d2)
> 
>     x    y
> 1   1    a
> 2   2    b
> 3   3    c
> 4   4    d
> 5   5    e
> 6   6    f
> 7   7    g
> 8   8    h
> 9   9    i
> 10 10    j
> 11  7 <NA>
> 21  8 <NA>
> 31  9 <NA>
> 41 10 <NA>
> 51 11 <NA>
> Warning message:
> invalid factor level, NAs generated in: "[<-.factor"(`*tmp*`,
ri, value = c("A",
> "B", "C", "D", "E")) 
> 
> 
> Things work correctly when the order of variables is the same:
> 
> 
>>d3=as.data.frame(list(x=7:11,y=LETTERS[1:5]))
>>rbind(d1,d3)
> 
>     x y
> 1   1 a
> 2   2 b
> 3   3 c
> 4   4 d
> 5   5 e
> 6   6 f
> 7   7 g
> 8   8 h
> 9   9 i
> 10 10 j
> 11  7 A
> 21  8 B
> 31  9 C
> 41 10 D
> 51 11 E
> 
> 
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