Hi divide and conquer
Split your data frame to required portions dat<-as.data.frame(cbind(rnorm(1:12),rnorm(1:12))) dat.s<-split(dat, rep(1:4, each=3)) apply lm to each portion sapply(dat.s, function(x) coef(lm(V2~V1, x))) 1 2 3 4 (Intercept) 1.21745328 -0.7783777 -0.1736094 0.1042114 V1 0.03639838 2.6203724 1.3167433 -0.2350888 Add those values to your data frame. hint: use rep(..., each=4) Regards Petr r-help-boun...@r-project.org napsal dne 07.07.2011 16:09:51: > Alfredo Alessandrini <alfreal...@gmail.com> > Odeslal: r-help-boun...@r-project.org > > 07.07.2011 16:09 > > Komu > > r-help@r-project.org > > Kopie > > Předmět > > [R] coefficients lm of data.frame > > Hi, > > I've a data frame like this: > > > as.data.frame(cbind(rnorm(1:12),rnorm(1:12))) > V1 V2 > 1 -1.30849402 -0.52094136 > 2 0.96157302 0.76217871 > 3 -0.44223351 -1.72630871 > 4 -0.10432438 -1.04732942 > 5 -1.38748914 0.95877311 > 6 -0.63965975 0.65494811 > 7 -0.24058318 0.19496830 > 8 -0.11172988 1.01680655 > 9 0.08065333 0.22168589 > 10 0.25196536 0.84619914 > 11 -0.59536986 -0.08243074 > 12 1.09115054 0.49822977 > > I need to add two columns as result of the fitting of linear model > based on a preset numbers of row. > > For example if I need to compute a lm each 4 rows, I get the > data.frame below, where intercept1 and coeff1 is obtained from V1 and > V2 of first 4 rows lm(V2 ~ V1), and so on... > > > V1 V2 "intercept" "coeff" > 1 0.6931694 0.05797771 intercept1 coeff1 > 2 -1.4069786 0.23983307 intercept1 coeff1 > 3 -1.4901708 0.45079601 intercept1 coeff1 > 4 0.2215696 1.87888983 intercept1 coeff1 > 5 -0.5828106 0.90376622 intercept2 coeff2 > 6 -0.7607985 0.71419938 intercept2 coeff2 > 7 0.1273495 0.06199312 intercept2 coeff2 > 8 -0.5612245 1.02223971 intercept2 coeff2 > 9 -0.1439178 0.92135354 intercept3 coeff3 > 10 -1.1011662 0.02894731 intercept3 coeff3 > 11 -0.4098710 -0.01231322 intercept3 coeff3 > 12 1.1511811 -0.63923140 intercept3 coeff3 > > > Thanks in advance, > > Alfredo > > ______________________________________________ > 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.