R repeat rows by vector and date - r

Question

I have a data frame with 275 different stations and 43 years seasonal data (October to next April, no need for May to Sept data)and 6 variables, here is a small example of the data frame with only one variable called value:
data <- data.frame(station=rep(1,6), year=rep(1969,6), month=c(10,10,10,10,11,11),day=c(1,8,16,24,1,9),value=c(1:6))
What I need is to fill the gap of day with daily date(eg:1:8) and the value of each row the average of the 8 days, it would be look like:
data1 <- data.frame(station=rep(1,40), year=rep(1969,40), month=c(rep(10,31),rep(11,9)),day=c(1:31,1:9),value=rep(c(1/7,2/8,3/8,4/8,5/8,6/8),c(7,8,8,8,8,1)))
I wrote some poor code and searched around the site, but unfortunately didn't work out, please help or better ideas would be appreciated.
station.date <- as.Date(with(data, paste(year, month, day, sep="-")))
for (i in 1:length(station.date)){
days <- as.numeric(station.date[i+1]-station.date[i]) #not working
data <- within(data, days <- c(days,1))
}
rows <- rep(1:nrow(data), times=data[ ,data$days])
rows <- ifelse(rows > 10, 0, rows) #get rid of month May to Sept
data <- data[rows, ]
data <- within(data, value1 <- value/days)
data <- within(data, dd <- ?) #don't know to change the repeated days to real days

Answer 1

I wrote some code that does the same things as your example, but probably You have to modyfi it in order to handle whole data set. I wasn't sure what to do with the last observation. Eventually I made a special case for it. If it should be divided by different number, You need just to replace 8 inside values <- c(values, tail(data$value, 1) / 8)
with that number. Moreover if you have all 275 stations in one data.frame, I think the best idea would be to split it, transform it separately and than cbind it.
data <- data.frame(station=rep(1,6), year=rep(1969,6), month=c(10,10,10,10,11,11),day=c(1,8,16,24,1,9),value=c(1:6))
station.date <- as.Date(with(data, paste(year, month, day, sep="-")))
d <- as.numeric(diff(station.date))
range <- sum(d) + 1
# create dates
dates <- seq(station.date[1], by = "day", length = range)
# create values
values <- unlist(sapply(1:length(d), function(i){
rep(data$value[i] / d[i] , d[i])
}))
# adding last observation
values <- c(values, tail(data$value, 1) / 8)
# create new data frame
data2 <- data.frame(station = rep(1, range),
year = as.numeric(format(dates, "%Y")),
month = as.numeric(format(dates, "%m")),
day = as.numeric(format(dates, "%d")),
value = values)
It could probably be optimised in some way, however I hope it helps too. Note how I extract year, month and day from dates.