[R] Bug in colnames of data.frames?

[Arne Henningsen]

Hi,

I am using R 1.9.1 on on i686 PC with SuSE Linux 9.0.

I have a data.frame, e.g.:

> myData <- data.frame( var1 = c( 1:4 ), var2 = c (5:8 ) )

If I add a new column by

> myData$var3 <- myData[ , "var1" ] + myData[ , "var2" ]

everything is fine, but if I omit the commas:

> myData$var4 <- myData[ "var1" ] + myData[ "var2" ]

the name shown above the 4th column is not "var4":

> myData
  var1 var2 var3 var1
1    1    5    6    6
2    2    6    8    8
3    3    7   10   10
4    4    8   12   12

but names() and colnames() return the expected name:

> names( myData )
[1] "var1" "var2" "var3" "var4"
> colnames( myData )
[1] "var1" "var2" "var3" "var4"

And it is even worse: I am not able to change the name shown above the 4th 
column:
> names( myData )[ 4 ] <- "var5"
> myData
  var1 var2 var3 var1
1    1    5    6    6
2    2    6    8    8
3    3    7   10   10
4    4    8   12   12

I guess that this is a bug, isn't it?

Arne