Not really, just the old saying that any piece of code can be made
twice as fast (which often holds true recursively). /Henrik
On Sun, May 31, 2009 at 1:58 PM, Wacek Kusnierczyk
<waclaw.marcin.kusnierc...@idi.ntnu.no> wrote:
> wow! :)
>
> vQ
>
> Henrik Bengtsson wrote:
>> library(gsubfn)
>> library(gtools)
>> library(rbenchmark)
>>
>> n <- 10000
>> df <- data.frame(
>> a = rnorm(n),
>> b = rnorm(n),
>> c = rnorm(n),
>> ip = replicate(n, paste(sample(255, 4), collapse='.'), simplify=TRUE)
>> )
>>
>> res <- benchmark(columns=c('test', 'elapsed'), replications=10, order=NULL,
>> peda = {
>> connection <- textConnection(as.character(df$ip))
>> o <- do.call(order, read.table(connection, sep='.'))
>> close(connection)
>> df[o, ]
>> },
>>
>> peda2 = {
>> connection <- textConnection(as.character(df$ip))
>> dfT <- read.table(connection, sep='.', colClasses=rep("integer",
>> 4), quote="", na.strings=NULL, blank.lines.skip=FALSE)
>> close(connection)
>> o <- do.call(order, dfT)
>> df[o, ]
>> },
>>
>> hb = {
>> ip <- strsplit(as.character(df$ip), split=".", fixed=TRUE)
>> ip <- unlist(ip, use.names=FALSE)
>> ip <- as.integer(ip)
>> dim(ip) <- c(4, nrow(df))
>> ip <- 256^3*ip[1,] + 256^2*ip[2,] + 256*ip[3,] + ip[4,]
>> o <- order(ip)
>> df[o, ]
>> },
>>
>> hb2 = {
>> ip <- strsplit(as.character(df$ip), split=".", fixed=TRUE)
>> ip <- unlist(ip, use.names=FALSE)
>> ip <- as.integer(ip);
>> dim(ip) <- c(4, nrow(df))
>> o <- sort.list(ip[4,], method="radix", na.last=TRUE)
>> for (kk in 3:1) {
>> o <- o[sort.list(ip[kk,o], method="radix", na.last=TRUE)]
>> }
>> df[o, ]
>> }
>> )
>>
>> print(res)
>>
>> test elapsed
>> 1 peda 4.12
>> 2 peda2 4.08
>> 3 hb 0.28
>> 4 hb2 0.25
>>
>
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>
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