Hi, Since you mentioned filtering the daily maximum temperature, this may help: datos<-read.table(text=" X, Ta, HR, RS, v 1/1/2010 1:00:00,5.28,100,0,2.3 1/1/2010 6:00:00,5.45,100,0,2.5 1/1/2010 11:00:00,5.51,100,0,1.1 2/1/2010 1:00:00,5.33,100,0,2.1 2/1/2010 6:00:00,5.48,100,0,2.3 2/1/2010 11:00:00,5.64,100,0,2.4 3/1/2010 1:00:00,5.12,100,0,2.0 3/1/2010 6:00:00,5.40,100,0,2.3 3/1/2010 11:00:00,5.32,100,0,1.7 ",sep=",",header=TRUE,stringsAsFactors=FALSE) library(zoo) z<-zoo(datos[,-1],order.by=as.POSIXct(datos[,1],format="%d/%m/%Y %H:%M:%S"))
aggregate(z$Ta,by=list(as.Date(index(z))),max) #gives the daily maximum temperatures #2010-01-01 2010-01-02 2010-01-03 # 5.51 5.64 5.40 For filtering the data: flag<-unlist(lapply(split(z,as.Date(index(z))),function(x) data.frame(x[,1]==max(x[,1]))),use.names=F) z1<-transform(z,flag=flag) z2<-z1[,1:4][z1$flag==1,] #filtered the maximum daily temp data z2 # Ta HR RS v #2010-01-01 11:00:00 5.51 100 0 1.1 #2010-01-02 11:00:00 5.64 100 0 2.4 #2010-01-03 06:00:00 5.40 100 0 2.3 str(z2) #‘zoo’ series from 2010-01-01 11:00:00 to 2010-01-03 06:00:00 # Data: num [1:3, 1:4] 5.51 5.64 5.4 100 100 100 0 0 0 1.1 ... #- attr(*, "dimnames")=List of 2 #..$ : NULL #..$ : chr [1:4] "Ta" "HR" "RS" "v" #Index: POSIXct[1:3], format: "2010-01-01 11:00:00" "2010-01-02 11:00:00" ... #or z3<-z z3$Max<-ave(z[,1],as.Date(index(z)),FUN=max) z4<-z3[,-5][z3$Ta==z3$Max,] z4 # Ta HR RS v #2010-01-01 11:00:00 5.51 100 0 1.1 #2010-01-02 11:00:00 5.64 100 0 2.4 #2010-01-03 06:00:00 5.40 100 0 2.3 Hope it helps A.K. ----- Original Message ----- From: Dominic Roye <dominic.r...@gmail.com> To: r-help@r-project.org Cc: Sent: Friday, November 23, 2012 1:04 PM Subject: [R] daily maximum temperature Hello, I want to filter the daily maximum temperature. For this i made this skript, but it come out wrong results. Can anybody help me? Thanks for your help! Best regards datos$X <- as.POSIXct(strptime(datos$X, "%d/%m/%Y %H:%M:%S")) z <- aggregate(zoo(datos$Ta), as.POSIXct(datos$X), max) > str(datos) 'data.frame': 17137 obs. of 5 variables: $ X : Factor w/ 17136 levels "00/01/1900 0:00:00",..: 2 3 4 5 6 7 8 9 10 11 ... $ Ta: num 5.28 5.45 5.54 5.54 5.51 5.51 5.5 5.56 5.58 5.63 ... $ HR: int 100 100 100 100 100 100 100 100 100 100 ... $ RS: int 0 0 0 0 0 0 0 0 0 0 ... $ v : num 2.3 2.5 1.1 2.3 2.2 2.1 2.2 2.9 2.4 2.6 ... str(z) ‘zoo’ series from 2010-01-01 00:10:00 to 2010-04-29 23:50:00 Data: num [1:17129] 5.28 5.45 5.54 5.54 5.51 5.51 5.5 5.56 5.58 5.63 ... Index: POSIXct[1:17129], format: "2010-01-01 00:10:00" "2010-01-01 00:20:00" "2010-01-01 00:30:00" "2010-01-01 00:40:00" ... > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
