Hi Rezvan, Yes, and you can get fertilizer2 like this: data1$fertilizer2<-data1fertilizer1*0.5
If I have the right idea, you want to substitute "fertilizer2" for "fertilizer1" in your new model of nitrate (concentration?). I don't think you want to include the coefficients (which are calculated by lm) into the formula for lm. Jim On Mon, Jun 27, 2016 at 11:15 AM, rezvan hatami <rezvan.hatami_...@yahoo.com > wrote: > For the sake of simplicity, I use my example to explain what I have > written: > > nutrient<-lm(nitrate~0.9*fertilizer-0.02*flowrate+0.5*rain) > datafram=data1 > > Change the value of fertelizer--à datafram=data2 > > predict(lm(nitrate~0.9*fertilizer2-0.02*flowrate+0.5*rain), datafram=data2 > > Is that better now? > > > > ------------------------------ > *From:* Jim Lemon <drjimle...@gmail.com> > *To:* rezvan hatami <rezvan.hatami_...@yahoo.com>; r-help mailing list < > r-help@r-project.org> > *Sent:* Monday, 27 June 2016, 10:28 > > *Subject:* Re: [R] How I can calculate the value of response variable > > Hi Rezvan, > This looks like a simple problem of solving linear equations (and very > much like a homework exercise). Therefore I won't actually give you the > answer, but suggest the steps for the solution. First you have to get the > data into R, so here is one way: > > rhdat<-read.table(text="season,site,nitrate,fertilizer1,flowrate > spring,site1,0.2,2,1 > spring,site2,1.2,3,1 > spring,site3,2.2,5,2 > summer,site1,3.2,1,2 > summer,site2,4.2,2,2 > summer,site3,5.2,3,2 > fall,site1,6.2,4,3 > fall,site2,7.2,5,3 > fall,site3,8.2,6,3 > winter,site1,9.2,4,4 > winter,site2,10.2,8,4 > winter,site3,11.2,9,4",sep=",",header=TRUE) > > You now have a data frame (rhdat) containing the values in your table. > > 1) calculate values for rain, which are missing from the table, e.g. > > rhdat$rain<-2*(rhdat$nitrate-0.9*rhdat$fertilizer+0.02*rhdat$flowrate) > > the above is an R expression to calculate the values for rain. > > 2) You may want explicitly calculate new values for rhdat$fertilizer, and > you have indicated that you already know how to do that. The above should > give you enough information about R syntax to translate the simple equation. > > 3) Now calculate new values for nitrate based on the equation you > supplied, but substituting the calculated values for rain and the modified > values for fertilizer. > > Jim > > > On Mon, Jun 27, 2016 at 9:43 AM, rezvan hatami < > rezvan.hatami_...@yahoo.com> wrote: > > Hi Jim > Thank you for your answer. nitrate=0.9*fertilizer-0.02*flowrate+0.5*rain > > my matrix: > season site nitrate fertilizer1 flow rate > spring site1 0.2 2 1 > spring site2 1.2 3 1 > spring site3 2.2 5 2 > summer site1 3.2 1 2 > summer site2 4.2 2 2 > summer site3 5.2 3 2 > fall site1 6.2 4 3 > fall site2 7.2 5 3 > fall site3 8.2 6 3 > winter site1 9.2 4 4 > winter site2 10.2 8 4 > winter site3 11.2 9 4 > > I would like to know, what will be the values for variable "nitrate" if I > divide the values of fertilizer by half and change the equation to: > > nitrate=0.9*fertilizer2-0.02*flowrate+0.5*rain > > in a matrix like: > > season site nitrate fertilizer2 flow rate > spring site1 0.2 1 1 > spring site2 1.2 1.5 1 > spring site3 2.2 2.5 2 > summer site1 3.2 0.5 2 > summer site2 4.2 1 2 > summer site3 5.2 1.5 2 > fall site1 6.2 2 3 > fall site2 7.2 2.5 3 > fall site3 8.2 3 3 > winter site1 9.2 2 4 > winter site2 10.2 4 4 > winter site3 11.2 4.5 4 > Would you please tell me how I can do this in R? > > Cheers > > Rezvan > > > ------------------------------ > *From:* Jim Lemon <drjimle...@gmail.com> > *To:* rezvan hatami <rezvan.hatami_...@yahoo.com>; r-help mailing list < > r-help@r-project.org> > *Sent:* Monday, 27 June 2016, 8:07 > *Subject:* Re: [R] How I can calculate the value of response variable > > Hi Rezvan, > I'll take a guess that you have been presented with a matrix of > coefficients. You probably know that a linear model is going to look > something like this: > > Y = ax1 + bx2 + cx3 ... > > So I will further guess that you want to infer a distribution of Y > (the response variable) from more than one set of coefficients. If my > guesses are correct, then you should be able to send an example that > shows what you have and what you want to get. > > Jim > > > On Sun, Jun 26, 2016 at 8:23 PM, rezvan hatami via R-help > <r-help@r-project.org> wrote: > > How I can calculate the value of response variable in a linear model of > a matrix of several variables?Can somebody please answer me? > > > > > > Cheers > > Rezvan Hatami > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > <http://www.r-project.org/posting-guide.html> > > and provide commented, minimal, self-contained, reproducible code. > > > > > > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
