On Mar 10, 2011, at 8:23 AM, Benjamin Stier wrote:
Hello list!
I have a data.frame which looks like this:
serv
datum op.read op.write read write
1 2011-01-29 10:00:00 0 0 0 0
2 2011-01-29 10:00:01 0 0 0 0
3 2011-01-29 10:00:02 0 0 0 0
4 2011-01-29 10:00:03 0 4 0 647168
5 2011-01-29 10:00:04 0 0 0 0
6 2011-01-29 10:00:05 0 14 0 1960837
7 2011-01-29 10:00:06 0 0 0 0
...
115 2011-01-30 10:00:54 0 0 0 0
116 2011-01-30 10:00:55 0 0 0 0
117 2011-01-30 10:00:56 0 0 0 0
118 2011-01-30 10:00:57 54 0 29184 0
119 2011-01-30 10:00:58 204 0 122880 0
120 2011-01-30 10:00:59 0 0 0 0
...
I want to compare read/write from each day. I already have a
solution, but it
is pretty slow.
See if this is any faster:
> aggregate(serv[, c("read", "write")], list(format(serv$datum, "%Y-
%m-%d")), sum)
Group.1 read write
1 2011-01-29 1021439 11726356
2 2011-01-30 1089534 4634910
# read the data
serv <- read.delim("cut.inp")
# Reformat the dates from the file
serv$datum <- strptime(serv$datum, "%Y-%m-%d %H:%M:%S")
# select all single days
dates.serv <- unique(strptime(serv$datum, format="%Y-%m-%d"))
# create a data.frame
values <- data.frame(row.names=1, datum=numeric(0),
write=numeric(0), read=numeric(0))
for(i in as.character(dates.serv)) {
# build up a values for a day-range
searchstart <- as.POSIXlt(paste(i, "00:00:00", sep=" "))
searchend <- as.POSIXlt(paste(i, "23:59:59", sep=" "))
# select all values from a specific day
day <- serv[(serv$datum >= searchstart & serv$datum <=
searchend),]
write <- as.numeric(sum(as.numeric(day$write)))
read <- as.numeric(sum(as.numeric(day$read)))
# add to the data.frame
values <- rbind(values, data.frame(datum=i, write=write,
read=read))
}
This is my first try using R for statistics so I'm sure this isn't
the best
solution.
The for-loop does it's job, but as I said is really slow. My data is
for 21
days and 1 line per second.
Is there a better way to select the date-ranges instead of a for-
loop? The
line where I select all values for "day" seems to be the heaviest.
Any idea?
Kind regards,
Benjamin
PS: I attached some sample data, in case you want to try for yourself.
<cut.inp>______________________________________________
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David Winsemius, MD
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
