Here are a few very simple notes I wrote up for someone a little while ago. They may be a bit of help.
R documentation is fairly confusing. The Help is almost alwas very complete but not necessarily easy to understand for neophite. :) Probably the first thing to do is to look into getting a decent editor for R. http://www.mediafire.com/?npzjnlgzg2y --- On Mon, 7/21/08, Williams, Robin <[EMAIL PROTECTED]> wrote: > From: Williams, Robin <[EMAIL PROTECTED]> > 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] __________________________________________________________________ [[elided Yahoo spam]] ______________________________________________ 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.
