help converting for loop to vector operation

library(ggplot2)
data(economics)

str(economics)

 # library(reshape)
d <- melt(economics, id="date")


foo <- function(var="pop", d, smooth=FALSE, ... ) {
       p <- qplot( data=subset(d, variable==var), x=date, y=value,  
geom=c('line','jitter'),
				ylab=var, main=var, colour=I("dark blue") )

       if ( smooth == TRUE ) {
               print("smoother requested...")
               return(print(p + stat_smooth() ) )
       }

return(print(p))
}

foo(d=d)


pdf()
# library(plyr)
l_ply(levels(d$variable), foo, d=d, smooth=T)
 # or lapply()
dev.off()

Dear List,

I have a wrapper function that draws a graph that I'd like to use in  
a vector-like manner.  The for-loop version I currently use is below.

library(ggplot2)
data(economics)
h <- 600
w <- 800

#----------------------------------------------------------
draw_metric_by_date <- function( df, i, smooth=FALSE, BASEPATH ) {
       mlabel  <- names(df)[i]
       qmetric <- qplot( data=df, x=date, y=df[,i],  
geom=c('line','jitter'), ylab=mlabel, main=mlabel, colour=I("dark  
blue") )

       if ( smooth == TRUE ) {
               print("smoother requested...")
               tmp     <- qmetric
               qmetric <- tmp + stat_smooth()
       }


       pngfn <- paste( BASEPATH, mlabel, ".png", sep="")
       print(pngfn)
       png( file=pngfn, height=h, width=w )
               print(qmetric)
               dev.off()
}


basepath <- "C:/tmp"
for ( i in c(2:6) ) {
       print(names(economics)[i])
       draw_metric_by_date( economics, i, smooth=TRUE, basepath )
}

Could someone show me how to do the same with a vector approach with  
an "apply" function ?

Many thanks,
Avram