bfatemi

require(stats)
## Extends the example for 'switch'
center <- function(x, type = c("mean", "median", "trimmed")) {
    type <- match.arg(type)
    switch(type,
           mean = mean(x),
           median = median(x),
           trimmed = mean(x, trim = .1))
}

reinholdsson

library(data.table)

x <- data.table(A = c(3,2,1), B = 4:6)
y <- data.table(A = 1:4, C = 5:8)
z <- data.table(A = 2:3, D = 5:6)

tbls <- list(x, y, z)
lapply(tbls, function(i) setkey(i, A))

merged <- Reduce(function(...) merge(..., all = T), tbls)