Slow example about plyr HOT 6 CLOSED

> system.time(ddply(d, .(grp1, grp2), summarise, avx = mean(x), avy=mean(y)))
   user  system elapsed 
103.711  21.499 125.523 
> i <- idata.frame(d)
> system.time(ddply(i, .(grp1, grp2), summarise, avx = mean(x), avy=mean(y)))
   user  system elapsed 
 73.654   0.251  74.008 

> system.time({
+   d$avx <- ave(d$x, list(d$grp1, d$grp2))
+   d$avy <- ave(d$y, list(d$grp1, d$grp2))
+ })
   user  system elapsed 
 39.300   0.279  40.809 
> 
> system.time({
+   d$avx <- ave(d$x, interaction(d$grp1, d$grp2, drop = T))
+   d$avy <- ave(d$y, interaction(d$grp1, d$grp2, drop = T))
+ })
   user  system elapsed 
  6.735   0.209   7.064 

> m <- function(df) { mean(df$x) }
> system.time(foo <- ddply(d, .(grp1, grp2), m,.progress='text'))
  |========================================================================| 100%
   user  system elapsed 
 45.826  21.846  69.497 
> system.time(foo <- ddply(d, .(grp1, grp2), avx=m,.progress='text'))
(USER INTERRUPT)
Timing stopped at: 97.059 51.123 150.527 
> system.time(foo <- ddply(d, .(grp1, grp2), summarise, avx = mean(x),.progress='text'))
  |========================================================================| 100%
   user  system elapsed 
115.335  63.607 180.758