Thanks for the clarification. I stand corrected. Dennis
On Sun, Oct 16, 2011 at 5:48 PM, gj <gaw...@gmail.com> wrote: > David is right. I am looking for the ecfd for fs$numstudents. The > other column is just an id. > > I guess I don't know how to read the R documentation when it comes to > functions. > > looking at the documentation, i now notice that it says "Compute an > empirical cummulative distribution function and not a vector. > > But still I would had assumed that in ecdf(x) ... the x is the argument. > > So ecdf(fs$numstudents)(unique(fs$numstudents)) > =============== ================== > function arguments > > Yes? But I can't read that from the documentation? I suspect it has > something to those dots .... in the arguments which I don't > understand. > > Why it says usage ecdf(x) when it's clearly not the case? > > I don't get it. > > Gawesh > > > On Sun, Oct 16, 2011 at 11:02 PM, David Winsemius > <dwinsem...@comcast.net> wrote: >> >> On Oct 16, 2011, at 3:53 PM, Dennis Murphy wrote: >> >>> Hi: >>> >>> I don't understand what you're attempting to do. Wouldn't courseid be >>> a categorical variable with a numeric label? If that is so, why are >>> you trying to compute an EDF? An EDF computes cumulative relative >>> frequency of a random variable, which by definition is numeric. If we >>> were talking about EDFs for a distribution of student course grades on >>> a numeric point system by course, that would make some sense, but I >>> don't see how the course IDs themselves qualify as being on an >>> interval scale of measurement. Could you clarify your intent? >> >> Huh? gawesh asked for ecdf on numstrudents (not courseid) ... pretty >> clearly a numeric value for which an ECDF should make sense. >> >> -- >> David. >> >> -- >>> >>> Dennis >>> >>> On Sun, Oct 16, 2011 at 8:31 AM, gj <gaw...@gmail.com> wrote: >>>> >>>> Hi, >>>> Newbie here. I read the R for Beginners but i still don't get this. >>>> >>>> I have the following data (this is just an example) in a CSV file: >>>> >>>> courseid numstudents >>>> 101 209 >>>> 141 13 >>>> 246 140 >>>> 263 8 >>>> 321 10 >>>> 361 10 >>>> 364 28 >>>> 365 25 >>>> 366 23 >>>> 367 34 >>>> >>>> I load my data using: >>>> >>>> fs<-read.csv(file="C:\\num_students_inallmodules.csv",header=T, sep=',') >>>> >>>> I want to get the ecdf. So, I looked at the ?ecdf which says >>>> usage:ecdf(x) >>>> >>>> So I expected ecdf(fs$numstudents) to work >>>> >>>> Instead it just returned: >>>> Call: ecdf(fs$numstudents) >>>> x[1:210] = 1, 2, 3, ..., 3717, 4538 >>>> >>>> After Googling, got this to work: >>>> ecdf(fs$numstudents)(unique(fs$numstudents)) >>>> >>>> But I don't understand why if the ?ecdf says usage is ecdf(x) ... I >>>> need to use ecdf(fs$numstudents)(unique(fs$numstudents)) to get this >>>> to work? >>>> >>>> Can somebody explain this to me? >>>> >>>> Regards >>>> Gawesh >>>> >>>> ______________________________________________ >>>> 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. >> >> David Winsemius, MD >> Heritage Laboratories >> West Hartford, CT >> >> > ______________________________________________ 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.
