Hi R helpers, I'm trying to create a count in R , but as there is no retain function like in SAS I'm running into difficulties. I have the following : Date_var and wish to obtain Date_var Count_var 01/01/2011 01/01/2011 1 01/01/2011 01/01/2011 2 02/01/2011 02/01/2011 1 02/01/2011 02/01/2011 2 02/01/2011 02/01/2011 3 02/01/2011 02/01/2011 4 03/01/2011 03/01/2011 1 03/01/2011 03/01/2011 2 03/01/2011 03/01/2011 3 03/01/2011 03/01/2011 4 03/01/2011 03/01/2011 5 03/01/2011 03/01/2011 6 03/01/2011 03/01/2011 7 As can be seen above the count var is re initialised every time a new date is found. I hope this is easy. Many thanks in advance for assistance. It is appreciated. Cheers Jon -- View this message in context: http://r.789695.n4.nabble.com/creating-a-count-variable-in-R-tp3334288p3334288.html Sent from the R help mailing list archive at Nabble.com.
Use cumsum() to count the change points:> Date_var <- as.Date(rep(c("2011-02-04","2011-02-07","2011-01-29"),c(2,3,1)))> data.frame(Date_var, count=cumsum(c(TRUE,Date_var[-1]!=Date_var[-length(Date_var)]))) Date_var count 1 2011-02-04 1 2 2011-02-04 1 3 2011-02-07 2 4 2011-02-07 2 5 2011-02-07 2 6 2011-01-29 3 Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com> -----Original Message----- > From: r-help-bounces at r-project.org > [mailto:r-help-bounces at r-project.org] On Behalf Of JonC > Sent: Thursday, March 03, 2011 1:58 PM > To: r-help at r-project.org > Subject: [R] creating a count variable in R > > Hi R helpers, > > I'm trying to create a count in R , but as there is no retain > function like > in SAS I'm running into difficulties. > > I have the following : > > Date_var and wish to obtain > Date_var > Count_var > 01/01/2011 > 01/01/2011 > 1 > 01/01/2011 > 01/01/2011 > 2 > 02/01/2011 > 02/01/2011 > 1 > 02/01/2011 > 02/01/2011 > 2 > 02/01/2011 > 02/01/2011 > 3 > 02/01/2011 > 02/01/2011 > 4 > 03/01/2011 > 03/01/2011 > 1 > 03/01/2011 > 03/01/2011 > 2 > 03/01/2011 > 03/01/2011 > 3 > 03/01/2011 > 03/01/2011 > 4 > 03/01/2011 > 03/01/2011 > 5 > 03/01/2011 > 03/01/2011 > 6 > 03/01/2011 > 03/01/2011 > 7 > > As can be seen above the count var is re initialised every > time a new date > is found. I hope this is easy. > > Many thanks in advance for assistance. It is appreciated. > > Cheers > > Jon > > > -- > View this message in context: > http://r.789695.n4.nabble.com/creating-a-count-variable-in-R-tp3334288p3334288.html> Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > 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. >
On Mar 3, 2011, at 3:58 PM, JonC wrote:> Hi R helpers, > > I'm trying to create a count in R , but as there is no retain > function like > in SAS I'm running into difficulties.Your data is not cut-pastable as presented but this should work: > dfrm$count_var <- ave(as.numeric(dfrm$Date_var), dfrm$Date_var, FUN=seq_along) > dfrm Date_var count_var 1 01/01/2011 1 2 01/01/2011 2 3 02/01/2011 1 4 02/01/2011 2 5 02/01/2011 3 6 02/01/2011 4 7 03/01/2011 1 8 03/01/2011 2 9 03/01/2011 3 10 03/01/2011 4 11 03/01/2011 5 12 03/01/2011 6 13 03/01/2011 7> > I have the following : > > Date_var and wish to obtain Date_var > Count_var > 01/01/2011 > 01/01/2011 > 1 > 01/01/2011 > 01/01/2011 > 2 > 02/01/2011 > 02/01/2011 > 1 > 02/01/2011 > 02/01/2011 > 2 > 02/01/2011 > 02/01/2011 > 3 > 02/01/2011 > 02/01/2011 > 4 > 03/01/2011 > 03/01/2011 > 1 > 03/01/2011 > 03/01/2011 > 2 > 03/01/2011 > 03/01/2011 > 3 > 03/01/2011 > 03/01/2011 > 4 > 03/01/2011 > 03/01/2011 > 5 > 03/01/2011 > 03/01/2011 > 6 > 03/01/2011 > 03/01/2011 > 7 > > As can be seen above the count var is re initialised every time a > new date > is found. I hope this is easy. > > Many thanks in advance for assistance. It is appreciated. > > Cheers > > Jon > > > -- > View this message in context: http://r.789695.n4.nabble.com/creating-a-count-variable-in-R-tp3334288p3334288.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > 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.David Winsemius, MD Heritage Laboratories West Hartford, CT
You can probably simplify this if you can assume that the dates are in sorted
order. Here is a way of doing it even if the days are in arbitrary order. The
count refers to the number of times that this date has appeared so far in the
sequence.
con <- textConnection("
01/01/2011
01/01/2011
02/01/2011
02/01/2011
02/01/2011
02/01/2011
03/01/2011
03/01/2011
03/01/2011
03/01/2011
03/01/2011
03/01/2011
03/01/2011
")
days <- scan(con, what = "")
close(con)
X <- model.matrix(~days-1)
XX <- apply(X, 2, cumsum)
dat <- data.frame(days = days, count = rowSums(X*XX))
dat
###
this uses days as a character string vector. If they are actual dates, then
convert them to character strings for this operation.
Bill Venables.
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of JonC
Sent: Friday, 4 March 2011 7:58 AM
To: r-help at r-project.org
Subject: [R] creating a count variable in R
Hi R helpers,
I'm trying to create a count in R , but as there is no retain function like
in SAS I'm running into difficulties.
I have the following :
Date_var and wish to obtain Date_var
Count_var
01/01/2011 01/01/2011
1
01/01/2011 01/01/2011
2
02/01/2011 02/01/2011
1
02/01/2011 02/01/2011
2
02/01/2011 02/01/2011
3
02/01/2011 02/01/2011
4
03/01/2011 03/01/2011
1
03/01/2011 03/01/2011
2
03/01/2011 03/01/2011
3
03/01/2011 03/01/2011
4
03/01/2011 03/01/2011
5
03/01/2011 03/01/2011
6
03/01/2011 03/01/2011
7
As can be seen above the count var is re initialised every time a new date
is found. I hope this is easy.
Many thanks in advance for assistance. It is appreciated.
Cheers
Jon
--
View this message in context:
http://r.789695.n4.nabble.com/creating-a-count-variable-in-R-tp3334288p3334288.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help at r-project.org mailing list
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.