http://finzi.psych.upenn.edu/R/library/fCalendar/html/3D-TimeDateSpecDates.html
try this also RSiteSearch("last day of the month") to get more pointers
- Regards,
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| Gaurav Yadav
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"Patnaik, Tirthankar " <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
05/10/2007 07:12 PM
To
<[email protected]>
cc
Subject
[R] Getting the last day of the month.
Hi,
Given a date, how do I get the last date of that month? I
have
data in the form YYYYMM, that I've read as a date using
> x$Date <-
as.Date(ISOdate(substr(x$YearEnd,1,4),substr(x$YearEnd,5,6),1))
But this gives the first day of the month. To get the last day of the
month, I tried
> as.Date(as.yearmon(x$Date,frac=0))
But I don't get the last day of the month here. (Tried frac=1 too.)
I then add a month to the date, substract one day from the resultant
date. But this wouldn't work for December.
> x$YearEnd
[1] 200203 200303 200403 200503 200603 200603 200312 200503 200603
200203 200303
[12] 200403 200503 200512 200612 200203 200303 200403 200503 200603
>
> x$Date <- as.Date(ISOdate(substr(x$YearEnd,1,4),
+ as.integer(substr(x$YearEnd,5,6))+1,
+ 1))-1
> x$Date
[1] "2002-03-31" "2003-03-31" "2004-03-31" "2005-03-31" "2006-03-31"
"2006-03-31"
[7] NA "2005-03-31" "2006-03-31" "2002-03-31" "2003-03-31"
"2004-03-31"
[13] "2005-03-31" NA NA "2002-03-31" "2003-03-31"
"2004-03-31"
[19] "2005-03-31" "2006-03-31"
So I add a year, and set the month to 1 in a quick function.
> GetEOM <- function(yyyymm=200406){
year <- as.integer(substr(yyyymm,1,4))
month <- as.integer(substr(yyyymm,5,6))
if (month==12){
date <- as.Date(ISOdate(year+1,1,1))-1
}else{
date <-
as.Date(ISOdate(year,month+1,1))-1
}
print(date)
}
x$Date <- as.vector(sapply(x$YearEnd,GetEOM))
str(x$Date)
Is there a simpler way to do this please?
TIA and best,
-Tir
Tirthankar Patnaik
India Strategy
Citigroup Investment Research
+91-22-6631 9887
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