My apologies. I negected to cc r-help. -- Bert
On Tue, Jun 18, 2019 at 11:21 AM Bert Gunter <bgunter.4...@gmail.com> wrote: > > I assume that 20000215 means year 2000, month 2, day 15. > I also assume that you want maxes for the first 2 weeks of a month, the > second 2 weeks, and any remaining days. > I also assume that this might be desired for arbitrary numbers of years, > months, and days. > > The following is one way to do this. As it's a slight pain to cut and > paste email data as text into R (use ?dput or R code to run to provide > example data instead), I just made up my own. You'll have to do the > following within a data frame through extraction or by using with() of > course. > > ## create some example data for 3 months in 2000 > d<- 2e7 +c(113:131,201:228, 301:330) ## dates > conc <- runif(length(d)) # concentrations > > ## convert the date to character to extract year, month, and day > cdate <- as.character(d) > ## use substr to to the extraction > year <- substr(cdate,1,4) > mon <- substr(cdate,5,6) > day <- substr(cdate, 7,8) > > ## convert day to numeric and use cut() to group into the biweekly periods. > d14 <- cut(as.numeric(day), c(0,14.5,28.5, 32)) > > ## Use tapply() to create your desired table of results. > tapply(conc, list(year, d14, mon), max, na.rm = TRUE) > > ## Results > > , , 01 > > (0,14.5] (14.5,28.5] (28.5,32] > 2000 0.7357389 0.9655391 0.7962965 > > , , 02 > > (0,14.5] (14.5,28.5] (28.5,32] > 2000 0.8193979 0.9487207 NA > > , , 03 > > (0,14.5] (14.5,28.5] (28.5,32] > 2000 0.9718919 0.9997093 0.168659 > > > Cheers, > Bert > > Bert Gunter > > > > > On Tue, Jun 18, 2019 at 8:53 AM SITI AISYAH BINTI ZAKARIA < > aisyahzaka...@unimap.edu.my> wrote: > >> Hi, >> >> I'm Aisyah..I have a problem to run my R coding. I want to select maximum >> value according to week. >> >> here is my data >> >> Date O3_Conc >> 20000101 0.033 >> 20000102 0.023 >> 20000103 0.025 >> 20000104 0.041 >> 20000105 0.063 >> 20000106 0.028 >> 20000107 0.068 >> 20000108 0.048 >> 20000109 0.037 >> 20000110 0.042 >> 20000111 0.027 >> 20000112 0.035 >> 20000113 0.063 >> 20000114 0.035 >> 20000115 0.042 >> 20000116 0.028 >> >> I want to find the max value from column O3_Conc for only 14 days that >> refer to biweekly in month. And the next 14 days for the max value. >> >> I hope that I can get the result like this: >> >> Date Max O3_Conc >> 20000101 - 20000114 0.068 >> 20000115 - 20000129 0.061 >> >> I try many coding but still unavailable. >> >> this example my coding >> >> library(plyr) >> data.frame(CA0003) >> >> # format weeks as per requirement (replace "00" with "52" and >> adjust corresponding year) >> tmp <- list() >> tmp$y <- format(df$Date, format="%Y") >> tmp$w <- format(df$Date, format="%U") >> tmp$y[tmp$w=="00"] <- as.character(as.numeric(tmp$y[tmp$w=="00"]) - >> 14) >> tmp$w[tmp$w=="00"] <- "884" >> df$week <- paste(tmp$y, tmp$w, sep = "-") >> >> # get summary >> df2 <- ddply(df, .(week),transform, O3_Conc=max(O3_Conc)) >> >> # include week ending date >> tmp$week.ending <- lapply(df2$week, function(x) rev(df[df$week ==x, >> "O3_Conc"])[[1]]) >> df2$week.ending <- sapply(tmp$week.ending, max(O3_Conc, TRUE) >> >> output >> Site_Id Site_Location Date >> Year O3_Conc Month Day week >> 1 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000101 >> 2000 0.033 1 1 NULL-NULL >> 2 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000102 >> 2000 0.023 1 2 NULL-NULL >> 3 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000103 >> 2000 0.025 1 3 NULL-NULL >> 4 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000104 >> 2000 0.041 1 4 NULL-NULL >> 5 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000105 >> 2000 0.063 1 5 NULL-NULL >> 6 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000106 >> 2000 0.028 1 6 NULL-NULL >> 7 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000107 >> 2000 0.068 1 7 NULL-NULL >> 8 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000108 >> 2000 0.048 1 8 NULL-NULL >> 9 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000109 >> 2000 0.037 1 9 NULL-NULL >> 10 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000110 >> 2000 0.042 1 10 NULL-NULL >> 11 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000111 >> 2000 0.027 1 11 NULL-NULL >> >> >> >> >> -- >> This message has been scanned by E.F.A. Project and is believed to be >> clean. >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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. >> > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
