Benckmark: order

library(data.table)
library(rbenchmark)

df = data.frame(col1 = rnorm(1000000), col2 = rnorm(1000000))
dt = data.table(df)
dt_key = copy(dt)
setkey(dt_key, col1, col2)

replications = 100

Function to test order using data.frame:

order_df_shell = function(df) {
    temp = df
    temp[order(temp$col1, -temp$col2),]
}

Function to test order using data.frame:

order_df_radix = function(df) {
    temp = df
    temp[order(temp$col1, -temp$col2, method = "radix"),]
}

Function to test order using data.table:

order_dt = function(dt) {
    temp = copy(dt)
    temp[order(col1, -col2), ]
}

Function to test order using data.table with index:

order_dt_key = function(dt_key) {
    temp = copy(dt_key)
    temp[order(col1, -col2), ]
}

Here we use rbenchmark to test above two functions

within(benchmark(order_df_shell_out <- order_df_shell(df),
                 order_df_radix_out <- order_df_radix(df),
                 order_dt_out <- order_dt(dt),
                 order_dt_key_out <- order_dt_key(dt_key),
                 replications = replications,
                 columns=c('test', 'replications', 'elapsed', "relative")),
       { average = elapsed/replications })

##                                       test replications elapsed relative
## 2 order_df_radix_out <- order_df_radix(df)          100  27.598    4.508
## 1 order_df_shell_out <- order_df_shell(df)          100 267.067   43.624
## 4 order_dt_key_out <- order_dt_key(dt_key)          100   6.122    1.000
## 3             order_dt_out <- order_dt(dt)          100  14.862    2.428
##   average
## 2 0.27598
## 1 2.67067
## 4 0.06122
## 3 0.14862

identical(data.table(order_df_shell_out), order_dt_out)

## [1] TRUE

sessionInfo()

## R version 3.3.0 (2016-05-03)
## Platform: x86_64-pc-linux-gnu (64-bit)
## Running under: Ubuntu 14.04.4 LTS
## 
## locale:
##  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
##  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
##  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
##  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
##  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
## [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
## 
## attached base packages:
## [1] stats     graphics  grDevices utils     datasets  methods   base     
## 
## other attached packages:
## [1] rbenchmark_1.0.0 data.table_1.9.7
## 
## loaded via a namespace (and not attached):
##  [1] magrittr_1.5    formatR_1.3     tools_3.3.0     htmltools_0.3.5
##  [5] yaml_2.1.13     Rcpp_0.12.4     stringi_1.0-1   rmarkdown_0.9.6
##  [9] knitr_1.13      stringr_1.0.0   digest_0.6.9    evaluate_0.9