hadley wickham wrote:
> On Fri, May 8, 2009 at 10:11 AM, Romain Francois
> <romain.franc...@dbmail.com> wrote:
>
>> strapply in package gsubfn brings elegance here:
>>
>>
>>> txt <- '<foo>bar</foo>'
>>> rx <- "<(.*?)>(.*?)</(.*?)>"
>>> strapply( txt, rx, c , perl = T )
>>>
>> [[1]]
>> [1] "foo" "bar" "foo"
>>
>> Too bad you have to pay this on performance:
>>
>>
>>> txt <- rep( '<foo>bar</foo>', 1000 )
>>> rx <- "<(.*?)>(.*?)</(.*?)>"
>>> system.time( out <- strapply( txt, rx, c , perl = T ) )
>>>
>> user system elapsed
>> 2.923 0.005 3.063
>>
>>> system.time( out2 <- sapply( paste('\\', 1:3, sep=''), function(x){
>>>
>> + gsub(rx, x, txt, perl=TRUE)
>> + } ) )
>> user system elapsed
>> 0.011 0.000 0.011
>>
>> Not sure what the right play i
>>
>
> For me:
>
>
>> system.time( out <- strapply( txt, rx, c , perl = T ) )
>>
> user system elapsed
> 0.004 0.000 0.004
>
>
>> system.time( out2 <- sapply( paste('\\', 1:3, sep=''), function(x){
>>
> + gsub(rx, x, txt, perl=TRUE)
> + } ) )
> user system elapsed
> 0 0 0
>
for me:
txt <- '<foo>bar</foo>'
rx <- '<(.*?)>(.*?)</(.*?)>'
library(rbenchmark)
benchmark(replications=1000, columns=c('test', 'elapsed'),
order='elapsed',
sapply=sapply(paste('\\', 1:3, sep=''), function(x) gsub(rx, x,
txt, perl=TRUE)),
mapply=mapply(gsub, rx, paste('\\', 1:3, sep=''), txt, perl=TRUE),
strapply=strapply(txt, rx, c, perl=TRUE))
# 2 mapply 0.151
# 1 sapply 0.166
# 3 strapply 1.917
vQ
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