[R] how to calculate "conditional" mean?
Gabor Grothendieck
ggrothendieck at myway.com
Sun Dec 5 18:33:23 CET 2004
Place Dates in DF and use subset(DF, month == 2) in place of DF.
I think you need to reread the Introduction to R manual since you
should find this sort of question answered there. If not the pointers
I gave you should get you started.
Terry Mu <muster <at> gmail.com> writes:
:
: thank you,
:
: one more question:
:
: How can I list only values for given condition?
: for example, I want to see only data from febuary, i.e. month=2?
:
: On Sun, 5 Dec 2004 16:26:11 +0000 (UTC), Gabor Grothendieck
: <ggrothendieck <at> myway.com> wrote:
: > Terry Mu <muster <at> gmail.com> writes:
: >
: > :
: > : a data set like this:
: >
: >
: > :
: > : year month day count
: > : 2001 1 1 10
: > : 2001 1 2 11
: > : ....
: > : 2004 7 17 8
: > : ....
: > :
: > : basically it is a count of of some numbers everyday through a few years
: > :
: > : now I'd like to get the mean of the count for every day.
: > :
: > : I thought I can do this using for and ifelse,
: > : but is there a simple way to do this? I wish a function like
: > : mean(count, 'only when year, month, day are equal') could do this.
: >
: > You want to represent your dates as objects of the Date class
: > and then use tapply. (See ?as.Date, ?Date, ?tapply, ?paste, ?with.
: > Also look up ?aggregate and ?by and read about dates in R News 4/1.)
: > Assuming DF is your data frame:
: >
: > Dates <- with(DF,
: > as.Date( paste(year, month, day, sep="-") )
: > )
: > tapply(DF$count, Dates, mean)
: >
: >
: >
: > ______________________________________________
: > R-help <at> stat.math.ethz.ch mailing list
: > https://stat.ethz.ch/mailman/listinfo/r-help
: > PLEASE do read the posting guide! http://www.R-project.org/posting-
guide.html
: >
:
: ______________________________________________
: R-help <at> stat.math.ethz.ch mailing list
: https://stat.ethz.ch/mailman/listinfo/r-help
: PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
:
:
More information about the R-help
mailing list