Hi Greg - this is perfect - Thank You! Also, thanks to everyone for the other suggestions
Greg Snow-2 wrote: > > How about: > > x3 <- cumsum( x2* 0.24^(5:0) ) / 0.24^(5:0) > > with the 5 replaced by the length -1 for the more general case. > > -- > Gregory (Greg) L. Snow Ph.D. > Statistical Data Center > Intermountain Healthcare > greg.s...@imail.org > 801.408.8111 > > >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r- >> project.org] On Behalf Of Pele >> Sent: Monday, February 23, 2009 1:59 PM >> To: r-help@r-project.org >> Subject: [R] Formula that includes previous row values >> >> >> Hi R users, >> >> Is there an easy way in R to generate the results table below using >> table 1 >> and the formula (simplified version of the real problem)? It would be >> easy >> if I knew the R equivalent of SAS's retain function, but could not find >> one. >> >> Thanks in Advance for any help! >> >> table1: >> >> ID X2 X3 >> 1.00 1.00 0 >> 2.00 0.00 >> 3.00 1.00 >> 4.00 3058 >> 5.00 0.00 >> 6.00 6.00 >> >> Formula: X3 = x2 + (.24 * x3) >> >> where the values in the x3 column of the result table are retained from >> previous x3 rows.. Also the first x3 value is initialized to 0 to start >> >> e.g. >> for ID=1 we have 1 + .24(0) = 1.00 >> for ID=2 we have 0 + .24(1) = 0.24 >> for ID=3 we have 1 + .24(.24) = 1.06 >> for ID=4 we have 3058 + .24(1.06) = 3058.25 >> etc............. >> >> Results: >> ID X2 x3 >> 1.00 1.00 1.00 >> 2.00 0.00 0.24 >> 3.00 1.00 1.06 >> 4.00 3058 3058.25 >> 5.00 0.00 733.98 >> 6.00 6.00 182.16 >> -- >> View this message in context: http://www.nabble.com/Formula-that- >> includes-previous-row-values-tp22170010p22170010.html >> 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. > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/Formula-that-includes-previous-row-values-tp22170010p22173033.html 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.