Hi everyone, I am not new to R, but its been over a year since I've used it, so I don't remember how to do some things. I have a data set (in excel currently, but will be converted to text), that has date, country and price, with a price for every country for every date. I need to find the mean and median of the interval between price changes for each country and the mean and median percentage change for each price change within the data for a single country. How should I go about doing this? I'd appreciate any help. Jia Ying Mei
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Some idea of the the data looks like and what you want to do with it would be helpful. ?read.csv ?mean ?tapply On Tue, Jul 22, 2008 at 4:31 PM, Jia Ying Mei <jiamei at princeton.edu> wrote:> Hi everyone, > > I am not new to R, but its been over a year since I've used it, so I don't > remember how to do some things. > > I have a data set (in excel currently, but will be converted to text), that > has date, country and price, with a price for every country for every date. > I need to find the mean and median of the interval between price changes for > each country and the mean and median percentage change for each price change > within the data for a single country. > > How should I go about doing this? I'd appreciate any help. > > Jia Ying Mei > > ______________________________________________ > 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. >-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem you are trying to solve?
On Tue, 2008-07-22 at 16:31 -0400, Jia Ying Mei wrote:> Hi everyone, > > I am not new to R, but its been over a year since I've used it, so I > don't remember how to do some things. > > I have a data set (in excel currently, but will be converted to text), > that has date, country and price, with a price for every country for > every date. I need to find the mean and median of the interval between > price changes for each country and the mean and median percentage change > for each price change within the data for a single country. > > How should I go about doing this? I'd appreciate any help.Hi Jia, I'm not too sure what you mean by the second set of means and medians, but this should get you started: # first make up some data jym.df<-data.frame(country=rep(c("au","br""cn","in","us"),each=100), date=rep(as.Date("02/02/2008", format="%d/%m/%Y"),500)+sample(-40:40,500,TRUE), price=rnorm(500,100,20)) # get the intervals by country - have to create a new data frame jymint.df<-data.frame(country=rep(levels(jym.df$country),each=99), intervals=unlist(tapply(jym.df$date,jym.df$country,diff))) library(prettyR) # break down the intervals by country brkdn(intervals~country,jymint.df,num.desc=c("mean","median")) Jim