System timings for http://stackoverflow.com/questions/26436633/transforming-dataframe-into-expanded-matrix-in-r

SO26436633.R

library(splitstackshape)
library(reshape2)
library(dplyr)
library(tidyr)

dfx <- data.frame(Var1=c("A", "B", "C", "D", "B", "C", "D", "C", "D", "D"),
                  Var2=c("E", "E", "E", "E", "A", "A", "A", "B", "B", "C"),
                  Var1out = c(1,-1,-1,-1,1,-1,-1,1,-1,-1),
                  Var2out= c(-1,1,1,1,-1,1,1,-1,1,1))

dfx <- do.call(rbind, replicate(10000, dfx, FALSE))

fun1 <- function() {
  dfx <- copy(dfx)
  dfx %>%
    setnames(gsub("(Var)([0-9])(out)", "\\3\\2", names(dfx))) %>%
    mutate(id = sequence(nrow(dfx))) %>%
    merged.stack(var.stubs = c("Var", "out"), sep = "var.stubs") %>%
    dcast.data.table(id ~ Var, value.var = "out", fill = 0)
}

fun2 <- function() {
  cols <- unique(unlist(dfx[1:2]))
  M <- matrix(0, nrow = nrow(dfx), ncol = length(cols), dimnames = list(NULL, cols))
  M[cbind(sequence(nrow(dfx)), match(dfx$Var1, cols))] <- dfx$Var1out
  M[cbind(sequence(nrow(dfx)), match(dfx$Var2, cols))] <- dfx$Var2out
  M
}

fun3 <- function() {
  dfy <- data.frame(Var = unlist(dfx[, 1:2]), 
                    VarOut = unlist(dfx[, 3:4]),
                    indx = 1:nrow(dfx))
  acast(dfy, indx ~ Var, value.var = "VarOut", fill = 0)
}

fun4 <- function() {
  dfy <- data.frame(Var = unlist(dfx[, 1:2]), 
                    VarOut = unlist(dfx[, 3:4]),
                    indx = 1:nrow(dfx))
  spread(dfy, Var, VarOut , fill = 0)[, -1]
}

system.time(fun1())
#    user  system elapsed 
#     0.3     0.0     0.3 
system.time(fun2())
#    user  system elapsed 
#    0.30    0.00    0.29 
system.time(fun3())
#    user  system elapsed 
#    1.53    0.07    1.39 
system.time(fun4())
#    user  system elapsed 
#    1.53    0.01    1.30