lowess output looks wrong (PR#7891)
Just noticed nobody has commented on this, so I took a look, and I can't see the problem (2.1.0 looks the same as 2.1.1 to me). What is supposed to be wrong? Duncan Murdoch
On 5/23/2005 2:35 PM, pelzc at ohsu.edu wrote:
Full_Name: Carl Pelz Version: 2.1.0 & 2.0.1 OS: Windows 2000 Submission from: (NULL) (137.53.64.158) # Paste this all into an R session for a graphical demonstration of BUG... # I?ve found a bug in lowess in R versions 2.0.1 & 2.1.0 (Windows binary versions). # Running on Windows 2000 system. # Someone noticed a similar problem and reported it under ID 4459. # Data to reproduce... R <- c(3.0, 3.5, 4.5, 5.0, 10.0) T <- R T <- 1.5*T + 0.1*(T^2) # Bug in lowess (third y value is wrong in lowess output)... xin <- log2(R) yin <- log2(T) minVal <- min (xin, yin) maxVal <- max (xin, yin) plot (xin, yin, xlim=c(minVal, maxVal), ylim=c(minVal, maxVal)) lines (lowess(xin, yin, f = 2/3, iter = 3)) text(3.5, 2, "3rd lowess point is wrong.", col="red") text(3.5, 1.75, "Click for next graph.", col="red") locator (n=1, type="n") # lowess OK... xin <- log2(R) yin <- log2(T) minVal <- min (xin, yin) maxVal <- max (xin, yin) plot (xin, yin, xlim=c(minVal, maxVal), ylim=c(minVal, maxVal)) # f = 1/2 lines (lowess(xin, yin, f = 1/2, iter = 3)) text(3.5, 2, "OK with f = 1/2.", col="red") text(3.5, 1.75, "Click for next graph.", col="red") locator (n=1, type="n") # lowess OK... xin <- log2(R) yin <- log2(T) minVal <- min (xin, yin) maxVal <- max (xin, yin) plot (xin, yin, xlim=c(minVal, maxVal), ylim=c(minVal, maxVal)) # iter = 0 lines (lowess(xin, yin, f = 2/3, iter = 0)) text(3.5, 2, "OK with iter = 0.", col="red") text(3.5, 1.75, "Click for next graph.", col="red") locator (n=1, type="n") # Bug in lowess (forth y value is wrong in lowess output)... xin <- log2(R) yin <- log2(T) # Change xin[3] xin[3] <- 2.2 minVal <- min (xin, yin) maxVal <- max (xin, yin) plot (xin, yin, xlim=c(minVal, maxVal), ylim=c(minVal, maxVal)) lines (lowess(xin, yin, f = 2/3, iter = 3)) text(3.5, 2, "4th lowess point is wrong.", col="red") text(3.5, 1.75, "Done.", col="red")
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