R help - Jan 2013 - rbind: inconsistent behaviour with empty data frames?

The rbind on empty and nonempty data frames behaves inconsistently. I am
not sure if by design.

In the first example, first row is deleted, which may or may not be on
purpose:
df1 <- data.frame()
df2 <- data.frame(foo=c(1, 2), bar=c("a", "b"))
rbind(df1, df2)
    foo  bar
2   2     b

Now if we continue:
df1 <- data.frame(matrix(0, 0, 2))
names(df1) <- names(df2)
    foo bar
2     1   a
3     2   b
So now data frames combined successfully, but the row names have been
increased by one.

Finally, if row names are strings, it works okay:
row.names(df2) <- c("row1", "row2")
rbind(df1, df2)
          foo bar
row1    1   a
row2    2   b

Is this behaviour by design?

	[[alternative HTML version deleted]]

What version of R are you using? 
I cannot replicate your results with R 2.15.2:
> df1 <- data.frame()
> df2 <- data.frame(foo=c(1, 2), bar=c("a", "b"))
> rbind(df1, df2)
  foo bar
1   1   a
2   2   b
> df1 <- data.frame(matrix(0, 0, 2))
> names(df1) <- names(df2)
> rbind(df1, df2)
  foo bar
1   1   a
2   2   b

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Dmitrii I.
> Sent: Wednesday, January 02, 2013 2:09 PM
> To: r-help at r-project.org
> Subject: [R] rbind: inconsistent behaviour with empty data frames?
> 
> The rbind on empty and nonempty data frames behaves inconsistently. I
> am
> not sure if by design.
> 
> In the first example, first row is deleted, which may or may not be on
> purpose:
> df1 <- data.frame()
> df2 <- data.frame(foo=c(1, 2), bar=c("a", "b"))
> rbind(df1, df2)
>     foo  bar
> 2   2     b
> 
> Now if we continue:
> df1 <- data.frame(matrix(0, 0, 2))
> names(df1) <- names(df2)
>     foo bar
> 2     1   a
> 3     2   b
> So now data frames combined successfully, but the row names have been
> increased by one.
> 
> Finally, if row names are strings, it works okay:
> row.names(df2) <- c("row1", "row2")
> rbind(df1, df2)
>           foo bar
> row1    1   a
> row2    2   b
> 
> Is this behaviour by design?
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.

> What version of R are you using?
I am using version 2.15.1.

Suddenly everything works correctly too. I guess a restarting R did the 
trick.

On 01/02/2013 10:25 PM, David L Carlson wrote:
> What version of R are you using?
> I cannot replicate your results with R 2.15.2:
>
>> df1 <- data.frame()
>> df2 <- data.frame(foo=c(1, 2), bar=c("a", "b"))
>> rbind(df1, df2)
>    foo bar
> 1   1   a
> 2   2   b
>> df1 <- data.frame(matrix(0, 0, 2))
>> names(df1) <- names(df2)
>> rbind(df1, df2)
>    foo bar
> 1   1   a
> 2   2   b
>
> ----------------------------------------------
> David L Carlson
> Associate Professor of Anthropology
> Texas A&M University
> College Station, TX 77843-4352
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
>> project.org] On Behalf Of Dmitrii I.
>> Sent: Wednesday, January 02, 2013 2:09 PM
>> To: r-help at r-project.org
>> Subject: [R] rbind: inconsistent behaviour with empty data frames?
>>
>> The rbind on empty and nonempty data frames behaves inconsistently. I
>> am
>> not sure if by design.
>>
>> In the first example, first row is deleted, which may or may not be on
>> purpose:
>> df1 <- data.frame()
>> df2 <- data.frame(foo=c(1, 2), bar=c("a", "b"))
>> rbind(df1, df2)
>>      foo  bar
>> 2   2     b
>>
>> Now if we continue:
>> df1 <- data.frame(matrix(0, 0, 2))
>> names(df1) <- names(df2)
>>      foo bar
>> 2     1   a
>> 3     2   b
>> So now data frames combined successfully, but the row names have been
>> increased by one.
>>
>> Finally, if row names are strings, it works okay:
>> row.names(df2) <- c("row1", "row2")
>> rbind(df1, df2)
>>            foo bar
>> row1    1   a
>> row2    2   b
>>
>> Is this behaviour by design?
>>
>> 	[[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-
>> guide.html
>> and provide commented, minimal, self-contained, reproducible code.