Hi all,
I'm handling massive data.frames and matrices in R (3 x 400).
In the 1st column, say, I have 0s and 1s indicating rows that matter; other
columns have probability values.
One simple task I would like to do would be to get the column mean values for
signaled rows (the ones with 1)
set.seed(123)
N = 3
K = 400
theData = matrix(rnorm(N*K), ncol=K)
theData = as.data.frame(theData)
theData = cbind(indicator = sample(0:1, N, rep=T), theData)
system.time(results - colMeans(subset(theData, indicator == 1)))
user system elapsed
2.309 1.319 3.853
b
On Jul 20,
