[R] format for as.Date and inserting missing rows in a data frame

[arun]

Hi,
May be this helps:
dat <- read.table(text="Raingouge_number Station_number Year Month Day Rainfall
2004 2230 1951 1 1 2.60
2004 2230 1951 1 2 0.40
2004 2230 1951 1 3 0.00
2004 2230 1951 1 4 0.00
2004 2230 1951 1 5 0.20
2004 2230 1951 1 6 0.00
2004 2230 1951 1 7 0.00
2004 2230 1951 1 9 0.00
2004 2230 1951 1 10 0.00
2004 2230 1951 1 11 0.20",sep="",header=TRUE)
dat <-  within(dat,Date <- as.Date(paste(Year,Month,Day),format="%Y %m %d"))
dat2 <- data.frame(Date=seq(dat$Date[1],dat$Date[length(dat$Date)],by="day"))
 res <- merge(dat,dat2,all=TRUE)
res$Rainfall[is.na(res$Rainfall)] <- -999
res
A.K.




On Tuesday, March 4, 2014 5:58 AM, Stefano Sofia <stefano.sofia at regione.marche.it> wrote:
Dear R users,
I have a very long data frame (50 years, more than 1.5 million rows) of daily rainfall data from about 80 raingouges.
The data frame that I have been given looks like

Raingouge_number Station_number Year Month Day Rainfall
2004 2230 1951 1 1 2.60
2004 2230 1951 1 2 0.40
2004 2230 1951 1 3 0.00
2004 2230 1951 1 4 0.00
2004 2230 1951 1 5 0.20
2004 2230 1951 1 6 0.00
2004 2230 1951 1 7 0.00
2004 2230 1951 1 8 0.00
2004 2230 1951 1 9 0.00
2004 2230 1951 1 10 0.00
...

There could be some missing days. I have two questions.
1st question:
In order to handle eventual missing days I think that I have to transform three separate numbers (Year, Month and Day) to Date.
Is there a format in as.Date suitable for this transformation or before all I have to set all the months and days to two digits, remove spaces and then apply
as.Date with format "%Y%m%d"?

2nd question
In case of missing day, the corresponding row will be missing and then I have to insert this new row and put -999.9 as Rainfall. Is there an easy way to do that?


Thank you for your help
Stefano


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