Hello,Please keep cc-ing the list R-help is threaded and questions and answers might be of help to others in the future.
As for the question, see if the following code does what you want.First, create a logical index i of the months between 7 and 3 and use that index to subset the original data.frame. Then, a cumsum trick gives a vector M defining the data grouping. Group and compute the Value means with aggregate. Finally, since each group spans a year border, create a more meaningful Years column and put everything together.
df1 <- read.csv("mddat.csv")
i <- with(df1, (Month >= 7 & Month <= 12) | (Month >= 1 & Month <= 3))
df2 <- df1[i, ]
M <- cumsum(c(FALSE, diff(as.integer(row.names(df2))) > 1))
agg <- aggregate(Value ~ M, df2, mean)
Years <- sapply(split(df2$Year, M), function(x){paste(x[1],
x[length(x)], sep = "-")})
final <- cbind.data.frame(Years, Value = agg[["Value"]]) head(final) # Years Value #0 1975-1975 87.00000 #1 1975-1976 89.44444 #2 1976-1977 85.77778 #3 1977-1978 81.55556 #4 1978-1979 71.55556 #5 1979-1980 75.77778 Hope this helps, Rui Barradas Às 20:44 de 04/08/20, Md. Moyazzem Hossain escreveu:
Dear Rui, Thanks a lot for your help.It is working. Now I am also trying to find the average of values for *July 1975 to March 1976* and record as the value of the year 1975. Moreover, I want to continue it up to the year 2017. You may check the attached file for data (mddat.csv).I use the following function but got erroraggregate(Value ~ Year, data = subset(df1, Month >= 7 & Month <= 3), FUN = mean)Please help me again. Thanks in advance. Best Regards, MdOn Mon, Aug 3, 2020 at 11:28 PM Rui Barradas <ruipbarra...@sapo.pt <mailto:ruipbarra...@sapo.pt>> wrote:Hello, And here is another way, with aggregate. Make up test data. set.seed(2020) df1 <- expand.grid(Year = 2000:2018, Month = 1:12) df1 <- df1[order(df1$Year),] df1$Value <- sample(20:30, nrow(df1), TRUE) head(df1) #Use subset to keep only the relevant months aggregate(Value ~ Year, data = subset(df1, Month <= 7), FUN = mean) Hope this helps, Rui Barradas Às 12:33 de 03/08/2020, Rasmus Liland escreveu: > On 2020-08-03 21:11 +1000, Jim Lemon wrote: >> On Mon, Aug 3, 2020 at 8:52 PM Md. Moyazzem Hossain <hossai...@juniv.edu <mailto:hossai...@juniv.edu>> wrote: >>> Hi, >>> >>> I have a dataset having monthly >>> observations (from January to >>> December) over a period of time like >>> (2000 to 2018). Now, I am trying to >>> take an average the value from >>> January to July of each year. >>> >>> The data looks like >>> Year Month Value >>> 2000 1 25 >>> 2000 2 28 >>> 2000 3 22 >>> .... ...... ..... >>> 2000 12 26 >>> 2001 1 27 >>> ....... ........ >>> 2018 11 30 >>> 20118 12 29 >>> >>> Can someone help me in this regard? >>> >>> Many thanks in advance. >> Hi Md, >> One way is to form a subset of your >> data, then calculate the means by >> year: >> >> # assume your data is named mddat >> mddat2<-mddat[mddat$month < 7,] >> jan2jun<-by(mddat2$value,mddat2$year,mean) >> >> Jim > Hi Md, > > you can also define the period in a new > column, and use aggregate like this: > > Md <- structure(list( > Year = c(2000L, 2000L, 2000L, > 2000L, 2001L, 2018L, 2018L), > Month = c(1L, 2L, 3L, 12L, 1L, > 11L, 12L), > Value = c(25L, 28L, 22L, 26L, > 27L, 30L, 29L)), > class = "data.frame", > row.names = c(NA, -7L)) > > Md[Md$Month %in% > 1:6,"Period"] <- "first six months of the year" > Md[Md$Month %in% 7:12,"Period"] <- "last six months of the year" > > aggregate( > formula=Value~Year+Period, > data=Md, > FUN=mean) > > Rasmus > > ______________________________________________ > R-help@r-project.org <mailto: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.-- Este e-mail foi verificado em termos de vírus pelo softwareantivírus Avast. https://www.avast.com/antivirus ______________________________________________ R-help@r-project.org <mailto: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.
______________________________________________ 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.
