look at function lmList() from package 'nlme', e.g., # say 'dat' is you data.frame library(nlme) fm <- lmList(DrugLevel ~ Day | Participant, data = dat) fm summary(fm)
I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/(0)16/336899 Fax: +32/(0)16/337015 Web: http://med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm ----- Original Message ----- From: "stathelp" <[EMAIL PROTECTED]> To: <r-help@r-project.org> Sent: Sunday, December 02, 2007 11:33 PM Subject: [R] Help with a Loop > > I am having trouble getting a loop to work for the following > problem. Any > help would be much appreciated. Thanks. > > I need to find the slope and intercept from the linear regression of > Drug > Level on Day by Participant. There are a total of 37 Participants. I > need to > store the Participant, Label, Slope, and Intercept in a new data > frame. > > > This data is ordered by Participant number 37 total participants. A > sample > of the data is given below. > > > Label Participant Day DrugLevel > 17 0 1 15 1.84179 > 121 0 1 5 2.10772 > 147 0 1 7 3.00658 > 152 0 1 11 2.91729 > 250 0 1 10 2.75816 > 289 0 1 13 3.20468 > 321 0 1 6 2.43389 > 362 0 1 12 2.77770 > 433 0 1 9 3.03167 > 469 0 1 8 2.97613 > 475 0 1 14 2.86934 > 70 0 2 13 0.68022 > 210 0 2 8 1.41767 > 243 0 2 11 1.28867 > 246 0 2 9 1.53601 > 247 0 2 6 1.64863 > 280 0 2 5 1.19795 > 310 0 2 12 1.24440 > 343 0 2 10 1.18929 > 413 0 2 7 1.57207 > 41 0 3 7 1.87884 > 74 0 3 8 1.82477 > 100 0 3 5 2.09422 > 133 0 3 6 1.91853 > 134 0 3 12 0.90422 > 149 0 3 11 1.38232 > 172 0 3 10 1.55323 > 216 0 3 9 1.24088 > 65 0 4 8 2.49412 > 69 0 4 5 1.79840 > > This is my thought process of what the loop needs to do but I cant > get the > correct loop. > > X1=Day[Participant=="1"] > Y1=DrugLevel[Participant=="1"] > > Coeffs=function(X1,Y1) > { > lmfirst=lm(Y1~X1) > lmfirst$coefficients > } > > Coeffs(X1,Y1) > > # output slope and intercept here > # do same for the next participant > > X2=Day[Participant=="2"] > Y2=DrugLevel[Participant=="2"] > > Coeffs=function(X2,Y2) > { > lmfirst=lm(Y2~X2) > lmfirst$coefficients > } > > Coeffs(X2,Y2) > > # output slope and intercept here > # do same for the next participant > > X3=Day[Participant=="3"] > Y3=DrugLevel[Participant=="3"] > > Coeffs=function(X3,Y3) > { > lmfirst=lm(Y3~X3) > lmfirst$coefficients > } > > Coeffs(X3,Y3) > > # output slope and intercept here > # do same for the next participant > > # etc for the rest of the participants > > # any ideas? > > # thanks > > -- > View this message in context: > http://www.nabble.com/Help-with-a-Loop-tf4933354.html#a14120625 > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm ______________________________________________ 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.
