Variable Wildcard Value

 Sure thing.  I realize that it is an unusual request and not the type
 of thing that I have seen used in any other language that I know of.

So right now I am using some of the statistical functions of R to get
some summary statistics and visual output from this historic data set.
I have a lot functions that look something like this:

 summary(lm(SLV_DIE_PER[tontype==TONNAGE_TYPE]~SLV_PER_TON[tontype==TONNAGE_TYPE]))

 SLV_DIE_PER - being the percent of slaves that died between purchase
 and delivery
 SLV_PER_TON - being the number of slaves per standardized ton (ship capacity)
 tontype - being the type of ton that the ship capacity was recorded
 as.  There are various factors mostly in the form of 1,2,3,4,5...
 representing Spanish Ton, British Ton, etc.

 Now I want to run a simple linear model and graphs and other things by
 specifying TONNAGE_TYPE=1 or 2 etc.  Giving me a regression that is
 only using looking at a particular type of tonnage over that of
 another.

 All of that works fine.  But, it gets a little ugly when I want to
 generalize the linear model to include all values irrespective of
 tontype.  Of course I could duplicate and trim the statement as such:

 summary(lm(SLV_DIE_PER~SLV_PER_TON))

 I am sure you can see how a wildcard could be more important given a series
 of similar expressions.  Perhaps something that looks like this:

 summary(SLV_DIE_PER[(SLV_DIE_PER>=SLV_Min_Value)&(Nationality==Select_Nationality)&((SLV_PER_TON<=SLV_Max_Value))&(tontype==TONNAGE_TYPE)]))

 Well thanks for your interest.  Any suggestions that can help clean up
 my code could be extremely helpful right now.

 Btw thanks Dieter for that hint.  Not exactly what I was looking for
 but I am sure to use it in the future.

Romain.  Thanks for your code, though I don't see readily how to fit
"w" into your functions.  Perhaps you could add an additional line
between:

"is.na.wildcard <- function( x ) FALSE"
  

and
"> w == 1"

Thanks!
Francis


  

On Wed, Apr 1, 2009 at 2:02 AM, Patrick Burns <pburns at pburns.seanet.com> wrote:
    

I would be truly amazed if the answer were "yes".

I find this the most fascinating question on R-help
for a long time, maybe ever.  Can you tell us what
you have in mind and what your ultimate purpose is?

Patrick Burns
patrick at burns-stat.com
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of "The R Inferno" and "A Guide for the Unwilling S User")

Francis Smart wrote:
      

Is there a wildcard value for vector values in r?

For instance:


        

M <- *wildcard

          

(M==1)

          

TRUE


        

(M=="peanut butter")

          

TRUE


        

is.na(M)

          

FALSE

thanks,
Francis


        

--
Francis Smart
(406) 223-8108 cell