Hello Marwan: Marwan Khawaja wrote:>Hello, >I have 15 data points (weight at birth) by age which I want to interpolate back >in time (to 5 more age points). >Are you trying to extrapolate?>There are many functions in R to do this and I wonder if anyone has experience >in using these -- any preference/caveat etc? I am trying to find an alternative >to linear interpolation. >It depends of many things... Are you fitting a particular model? Is the linear model enough?>Using R 1.6.0 under windows >TIA Marwan > >-------------------------------------------------------------------------------- >-------------------------------------------------------- >Marwan Khawaja - http://webfaculty.aub.edu.lb/~mk36/ If you have MS >Internet Explorer! >-------------------------------------------------------------------------------- >-------------------------------------------------------- > >-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- >r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html >Send "info", "help", or "[un]subscribe" >(in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch >_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._ > > > >-- Kenneth Roy Cabrera Torres Celular +57 (315) 405 9339 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
"Marwan Khawaja" <mk36 at aub.edu.lb> writes:> I have 15 data points (weight at birth) by age which I want to > interpolate back in time (to 5 more age points).I'm not sure if I understand what you are asking. The phrase "back in time" seems to indicate extrapolation rather than interpolation.> There are many functions in R to do this and I wonder if anyone has > experience in using these -- any preference/caveat etc? I am trying > to find an alternative to linear interpolation.You could try interpSpline in the splines package. That produces a "natural spline" that can be used for interpolation within the range of the data or extrapolation beyond the range of the data. Linear extrapolation, based on the derivative of the fitted function at the end points, is used. -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Hello, I have 15 data points (weight at birth) by age which I want to interpolate back in time (to 5 more age points). There are many functions in R to do this and I wonder if anyone has experience in using these -- any preference/caveat etc? I am trying to find an alternative to linear interpolation. Using R 1.6.0 under windows TIA Marwan -------------------------------------------------------------------------------- -------------------------------------------------------- Marwan Khawaja - http://webfaculty.aub.edu.lb/~mk36/ If you have MS Internet Explorer! -------------------------------------------------------------------------------- -------------------------------------------------------- -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._