Difference between revisions of "Bsplines.R"
From Organic Design wiki
(library(splines)) |
(Seems to be a bug in variable naming from 'fit') |
||
| Line 1: | Line 1: | ||
# {{R}} | # {{R}} | ||
library(splines) | library(splines) | ||
| − | + | ||
# p38 | # p38 | ||
pos <- function(x) ifelse(x>0, x, 0) | pos <- function(x) ifelse(x>0, x, 0) | ||
| Line 8: | Line 8: | ||
knot <- 4 | knot <- 4 | ||
plot(x,y) | plot(x,y) | ||
| − | X <- cbind("int"=1,"x"=x,"x2"=x^2,"x3"=x^3, "xknot"=pos(x-knot)^3) | + | #X <- cbind("int"=1,"x"=x,"x2"=x^2,"x3"=x^3, "xknot"=pos(x-knot)^3) |
| − | fit <- lm(y~X-1) | + | #fit <- lm(y~X-1) |
| + | |||
| + | fit <- lm(y~1+x+x^2+x^3+pos(x-knot)^3) | ||
xx <- seq(1,7, length=200) | xx <- seq(1,7, length=200) | ||
| − | XX <- cbind(" | + | XX <- cbind("x"=xx) |
lines(xx, predict(fit, as.data.frame(XX))) # Bug here | lines(xx, predict(fit, as.data.frame(XX))) # Bug here | ||
abline(v=knot, lty=2) | abline(v=knot, lty=2) | ||
X | X | ||
| + | |||
# p41 | # p41 | ||
par(mfrow=c(2,1)) | par(mfrow=c(2,1)) | ||
Revision as of 02:23, 17 October 2007
Code snipits and programs written in R, S or S-PLUS library(splines)
- p38
pos <- function(x) ifelse(x>0, x, 0) x <- 1:7 y <- c(8,3,8,5,9,14,11) knot <- 4 plot(x,y)
- X <- cbind("int"=1,"x"=x,"x2"=x^2,"x3"=x^3, "xknot"=pos(x-knot)^3)
- fit <- lm(y~X-1)
fit <- lm(y~1+x+x^2+x^3+pos(x-knot)^3) xx <- seq(1,7, length=200) XX <- cbind("x"=xx) lines(xx, predict(fit, as.data.frame(XX))) # Bug here abline(v=knot, lty=2) X
- p41
par(mfrow=c(2,1)) knots <- c(1:3,5,7,8,10) atx <- seq(0:11, by=0.1) for(ord in 1:4) { B <- bs(x=atx, degree=ord, knots=knots, intercept=TRUE, Boundary.knots=c(0,11)) matplot(atx, B[,1], type="l", ylim=0:1, lty=2) matlines(atx, B[,-1], col=1, lty=1) title(paste("B splines of order", ord)) abline(v=knots, lty=2) }
