R help - Mar 2003 - Strange and disturbing bug

How about this one? If I set a variable in a data.frame with a two-
part name including a dot (say y.pair), and if the variable with the 
name of the first part (y) doesn't but I ask for it's value I get the 
value of the two-part name. Ie set fred$x.pair and print the value of 
fred$x it gives me the value I set to fred$x.pair. Weird and 
somewhat disturbing!
Maybe an example makes it clearer:


  Dr Steve Roberts 
  steve.roberts at man.ac.uk

Senior Lecturer in Medical Statistics,
CMMCH NHS Trust and University of Manchester Biostatistics Group,
0161 275 5192 / 0161 276 5785

Hi Steve.

This is very much a feature, not a bug, and unless I am mistaken does
not relate to the use of a "two part name" (i.e. x.pair). 

The $ operator does partial matching on the names.  So fred$x yields
a partial match for fred$x.pair and gives you what you most likely
wanted.  Of course, using fred$x.pair makes this more readable in a
function/software, but partial matching is very convenient for
interactive use.

 D.


Steve Roberts wrote:
> How about this one? If I set a variable in a data.frame with a two-
> part name including a dot (say y.pair), and if the variable with the 
> name of the first part (y) doesn't but I ask for it's value I get
the
> value of the two-part name. Ie set fred$x.pair and print the value of 
> fred$x it gives me the value I set to fred$x.pair. Weird and 
> somewhat disturbing!
> Maybe an example makes it clearer:
> 
> 
>   Dr Steve Roberts 
>   steve.roberts at man.ac.uk
> 
> Senior Lecturer in Medical Statistics,
> CMMCH NHS Trust and University of Manchester Biostatistics Group,
> 0161 275 5192 / 0161 276 5785
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
-- 
_______________________________________________________________

Duncan Temple Lang                duncan at research.bell-labs.com
Bell Labs, Lucent Technologies    office: (908)582-3217
700 Mountain Avenue, Room 2C-259  fax:    (908)582-3340
Murray Hill, NJ  07974-2070       
         http://cm.bell-labs.com/stat/duncan

What a wonderful set of people you are! - I 
solved by own problem, deleted the message and 
got 3 replies before I realised I'd hit "send" 
rather then "delete". 

Steve.
 
  Dr Steve Roberts 
  steve.roberts at man.ac.uk

Senior Lecturer in Medical Statistics,
CMMCH NHS Trust and University of Manchester Biostatistics Group,
0161 275 5192 / 0161 276 5785