Thanks very much for this. The dates are in fact in 3-character form (i.e. sep and not sept). Any suggestions as to where one can start to learn the R language? Up until now, I have only entered simple commands in the terminal.
Best wishes, Robin Williams Met Office summer intern - Health Forecasting [EMAIL PROTECTED] -----Original Message----- From: Gabor Grothendieck [mailto:[EMAIL PROTECTED] Sent: Monday, July 21, 2008 3:26 PM To: Williams, Robin Cc: R-help@r-project.org Subject: Re: [R] Subsetting data by date Continuing on, to just get points from May to Sep mo <- as.numeric(format(time(z), "%m")) z.summer <- z[mo >= 5 & mo <= 9] If in your case z is multivariate rather than univariate (as it is in our example) then it would be: z.summer <- z[mo >= 5 & mo <= 9, ] On Mon, Jul 21, 2008 at 9:55 AM, Gabor Grothendieck <[EMAIL PROTECTED]> wrote: > Try this: > > Lines <- "Date,Temp > 1-Apr-1997,50 > 3-Sept-2001,60" > > library(zoo) > > # function to reduce 4 char mos to 3 char convert.date <- function(x, > format) as.Date(sub("(-...).-", "\\1-", x), format) > > # z <- read.zoo("myfile.csv", header = TRUE, sep = ",", FUN = > convert.date, format = "%d-%b-%Y") z <- > read.zoo(textConnection(Lines), header = TRUE, sep = ",", FUN = > convert.date, format = "%d-%b-%Y") > > plot(z) > > If the dates are actually three letters, i.e. Sep and not Sept, then > you could eliminate convert.date and simplify the read.zoo line to: > > z <- read.zoo(textConnection(Lines), header = TRUE, sep = ",", format > = "%d-%b-%Y") > > See the zoo package documentation and its three vignettes as well as > ?read.zoo ?strptime and ?plot.zoo and also look at the dates article in R News 4/1. > > > On Mon, Jul 21, 2008 at 9:31 AM, Williams, Robin > <[EMAIL PROTECTED]> wrote: >> Hi all, >> Firstly I appologise if this question has been answered previously, >> however searching of the archives and the internet generally has not >> yielded any results. >> >> I am looking in to the effects of summer weather conditions >> (temperature, humidity etc), on the incidences of a breathing >> disorder brought on through smoking (COPD). I am fairly new to R and >> completely new to the idea of writing R scripts, subsetting >> dataframes etc. I am working on a 12 week summer placement at the Met >> Office, UK, having just finished my second year of a mathematics course at university. >> >> Basically I have data between January 1 1997 and December 31 2007. >> However as I am only interest in the summer months (which I have >> defined to be between May 1 and September 30), I would like to >> extract the relevant data in R in a timely manner. Obviously I could >> go and open my csv files in excel, cut and paste the relevant data, >> etc, however I would like to maximise R's potential as I feel it will >> stand me in better stead in the long run. >> Currently the dates are in the form >> 1-Apr-1997, >> 3-Sept-2001, >> etc. >> I will create a data.frame with date as one of the variables, the >> others being (initially) temperature, humidity, and Admissions (the >> number of hospital admissions for COPD exaserbations). >> Please could somebody tell me if there is a simple way to extract >> the data I want, and if so perhaps a sample command to get me going? >> Do I first need to format the dates to some numeric-only format? As I >> say, I could use Excel to create the files in the right format, but I >> will be dealing with a lot more variables in the future (perhaps up >> to 8) and so this will become a pain-staking process. >> >> Please reply either on or off list. >> >> Many thanks for any help. >> Robin Williams >> Met Office summer intern - Health Forecasting >> [EMAIL PROTECTED] >> >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@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. >> > ______________________________________________ R-help@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.
