Here is another way, not necessarily better.
Since you didn't provide any column names, let df$tm refer to the column of times, which I will assume is a vector of character strings.
## as a one-liner, results in a character object (the '2004-5-1' is arbitrary, use any valid date)
minute <- format(as.POSIXct(paste('2004-5-1',df$tm,sep='-')),'%M')
## in multiple lines, making it possible to plot the data with an axis having an accurate time scale
tm <- as.POSIXct(paste('2004-5-1',df$tm,sep='-'))
## as above, minute is a character object minute <- format(tm,'%M')
## or this way, minute is a POSIXt object, also suitable for use with a time-scaled plot
minute <- trunc(tm,'mins')
-Don
At 10:52 PM +0200 5/26/04, Wolski wrote:
Hi! I would extract the minutes from the time using sub (see ?sub) or (?grep) than use them as factors (?as.factors) and finally ?tapply
eg. tt<-1:10 fac<-c(rep(0,4),rep(1,6)) # here put the minutes from the time fac [1] 0 0 0 0 1 1 1 1 1 1 fac<-as.factor(fac) fac [1] 0 0 0 0 1 1 1 1 1 1 Levels: 0 1
tapply(t,fac,max) 0 1 4 10
Sincerely Eryk.
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On 5/26/2004 at 3:00 PM [EMAIL PROTECTED] wrote:
Hi, i need select data from data frame, for example: x is a data frame with values in jump to 5 seconds 12:10:00 51 //one minute 12:10:05 63 12:10:10 75 12:10:15 88 .. 12:10:59 45 12:11:00 46 //another minute 12:11:05 11 .. Have a command what to select the data minute to minute, for example in the example above i need the maximun values minute to minute 1� minute-->88 2� minute--> 46 Thanks Ruben
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Dipl. bio-chem. Eryk Witold Wolski @ MPI-Moleculare Genetic Ihnestrasse 63-73 14195 Berlin 'v' tel: 0049-30-83875219 / \ mail: [EMAIL PROTECTED] ---W-W---- http://www.molgen.mpg.de/~wolski
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-- -------------------------------------- Don MacQueen Environmental Protection Department Lawrence Livermore National Laboratory Livermore, CA, USA
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