A quirk in `transform'? 

> df <- data.frame(x=1:3, y=4:6, z=7:9); df
  x y z
1 1 4 7
2 2 5 8
3 3 6 9
> transform(df,z=z)
  x y z
1 1 4 7
2 2 5 8
3 3 6 9
> transform(df,y=y)
  x y z
1 1 4 7
2 2 5 8
3 3 6 9
> transform(df,x=x)
Error in transform(df, x = x) : Object "x" not found
> 

_              
platform i386-pc-mingw32
arch     i386           
os       mingw32        
system   i386, mingw32  
status                  
major    1              
minor    6.2            
year     2003           
month    01             
day      10             
language R              

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Best, 
Steve Wisdom, CT, USA 


