[R] r scripting

[Don MacQueen]

For the mean() example, I believe this should work (untested)

   for (var in names(Dataset))  print( mean( Dataset[[var]] , na.rm=TRUE ) )
or
   for (var in names(Dataset))  print( mean( Dataset[,var] , na.rm=TRUE ) )


But it's harder with lm, glm, and friends. For them I think maybe you 
can do it by constructing a formula object, see ?formula.
Maybe something like,
     tmpf <- as.formula( paste( var, ' ~var1 + var2 + var3') )
     glm( tmpf , Dataset)
inside the loop, but I haven't done this and am not an expert.

Here's a quick example:

>  foo <- data.frame( x=1:10, y=rnorm(10) )
>  ick <- as.formula( ' x ~ y')   
>  lm(ick,foo)

Call:
lm(formula = ick, data = foo)

Coefficients:
(Intercept)            y 
       5.895        2.158 

## compare with:
>  lm(x~y,foo)

Call:
lm(formula = x ~ y, data = foo)

Coefficients:
(Intercept)            y 
       5.895        2.158 


But it's a question that comes up periodically on r-help, so I'd also 
suggest searching the archives.

-Don

At 10:50 AM -0400 6/18/09, Jon Erik Ween wrote:
>Hi!
>
>I have a dataset with some 300+ variables and 2000+ records. I'd like to grind
>through a bunch of analyses on the variables by using a script, but can't
>figure out how to refer to variable names properly. For some of the simpler
>stuff I use various "apply" functions, but for others (like t-tests 
>etc) I need
>by command procedures. I've tried various flavors of "for(var in
>names(Dataset)){...}" but this does not work consistently. Actually, "for(var
>in names(Dataset){print var}, seems to work perfectly, giving a list of
>variable names, but "for(var in names(Dataset)){mean(var, na.rm=T) or for(var
>in names(Dataset)){glm(var~var1+var2+var3....} do not.
>
>Any suggestions about how best to go about this?
>
>Thanks
>
>Jon
>
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-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062