spped up a function

Hi Petr, yes the function basically consists on merging two time series with different time intervals: one regular 'GPS' and one irregular 'xact' (the latter containing the binomial variable 'wd' that I want to add to 'GPS'.
Apparently my attachments did not go through. Here you have the dputs you requested plus the desired result based on them:

head(xact)
Ringjul ? timepos ? actwd
6106933 15135 2011-06-10 04:36:15 ?3822 dry
6106933 15135 2011-06-10 05:39:57 ? ?27 wet
6106933 15135 2011-06-10 05:40:24 ? ?60 dry
6106933 15135 2011-06-10 05:41:24 ? ? 6 wet
6106933 15135 2011-06-10 05:41:30 ? 753 dry
6106933 15135 2011-06-10 05:54:03 ? ?78 wet
6106933 15135 2011-06-10 05:55:21 ? ?15 dry
6106933 15135 2011-06-10 05:55:36 ? ?18 wet

head(GPS1, 16) and desired result (added column wd)?

? ? ? Ring ? jul ? ? ? ? ? ? timeposwd
5 ?6106933 15135 2011-06-10 04:39:00dry
6 ?6106933 15135 2011-06-10 04:44:00dry
7 ?6106933 15135 2011-06-10 04:49:00dry
8 ?6106933 15135 2011-06-10 04:54:00dry
9 ?6106933 15135 2011-06-10 04:59:00dry
10 6106933 15135 2011-06-10 05:04:00dry
11 6106933 15135 2011-06-10 05:09:00dry
12 6106933 15135 2011-06-10 05:13:00dry
13 6106933 15135 2011-06-10 05:18:00dry
14 6106933 15135 2011-06-10 05:23:00dry
15 6106933 15135 2011-06-10 05:28:00dry
16 6106933 15135 2011-06-10 05:33:00dry
17 6106933 15135 2011-06-10 05:38:00dry
18 6106933 15135 2011-06-10 05:43:00dry
19 6106933 15135 2011-06-10 05:48:00dry
20 6106933 15135 2011-06-10 05:53:00dry

Santi

________________________________
From: PIKAL Petr <petr.pikal at precheza.cz>
To: Santiago Guallar <sguallar at yahoo.com>; r-help <r-help at r-project.org> 
Sent: Monday, July 8, 2013 11:34 AM
Subject: RE: [R] spped up a function


Hi

It seems to me, that you basically want merge, but I can miss the point. Try post

dput(head(xact))
dput(head(GPS))

and what shall be desired result based on those 2 datasets.

Regards
Petr


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Santiago Guallar
Sent: Tuesday, July 02, 2013 7:47 PM
To: r-help
Subject: [R] spped up a function

Hi,

I have written a function to assign the values of a certain variable
'wd' from a dataset to another dataset. Both contain data from the
same?time period but differ in the length of their time intervals:
'GPS' has regular 10-minute intervals whereas 'xact' has

irregular

intervals. I attached simplified text versions from write.table. You
can also get a dput of 'xact' in this address:
http://www.megafileupload.com/en/file/431569/xact-dput.html).
The original objects are large and the function takes almost one hour
to finish.
Here's the function:

fxG= function(xact, GPS){
l <- rep( 'A', nrow(GPS) )
v <- unique(GPS$Ring) # the process is carried out for several
individuals identified by 'Ring'
for(k in 1:length(v) ){
I = v[k]
df <- xact[xact$Ring == I,]
for(i in 1:nrow(GPS)){
if(GPS[i,]$Ring== I){# the code runs along the whole data.frame for
each i; it'd save time to make it stop with the last record of each i
instead u <- df$timepos <= GPS[i,]$timepos # fill vector l for each
interval t from xact <= each interval from GPS (take the max if

there's

1 interval) l[i] <- df[max( which(u == TRUE) ),]$wd } } } return(l)}

vwd <- fxG(xact, GPS)


My question is: how can I speed up (optimize) this function?

Thank you for your help