Problem with a LOESS curve
Your x values aren't in increasing order. When you plot lines(x, yfit), it joins the points in the order you give them, which jumps back and forth. To fix, try o <- order(x) lines(x[o], yfit[o], col="green", lwd=2) Duncan Murdoch
On 09/01/2021 2:58 p.m., varin sacha via R-help wrote:
############################## #DATA y<-c(499,491,500,517,438,495,501,525,516,494,500,453,479,481,505,465,477,520,520,480,477,416,502,503,497,513,492,469,504,482,502,498,463,504,495) x<-c(499,496,424,537,480,484,503,575,540,436,486,506,496,481,508,425,501,519,546,507,452,498,471,495,499,522,509,474,502,534,504,466,527,485,525) #PLOT plot(x,y) #GAM library(mgcv) fit3=gam(y~s(x,bs='ps')) x.new<- seq(range(x)[1], range(x)[2], len=1000) gamfit.new <- as.vector(predict.gam(fit3,data.frame(x=x.new),type="response")) lines(x.new, gamfit.new, col="red", lwd=2) # LOESS mod=loess(y~x, span=0.8) yfit=predict(mod,newdata=x) lines(x,yfit,col="green",lwd=2) ##############################