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x |
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y |
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iter |
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bend |
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xout |
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outfun |
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... |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | ##---- Should be DIRECTLY executable !! ----
##-- ==> Define data, use random,
##-- or do help(data=index) for the standard data sets.
## The function is currently defined as
function (x, y, iter = 20, bend = 2 * sqrt((ncol(x) + 1)/nrow(x)),
xout = FALSE, outfun = outpro, ...)
{
x <- as.matrix(x)
p1 <- ncol(x) + 1
p <- ncol(x)
xy <- cbind(x, y)
xy <- elimna(xy)
x <- xy[, 1:p]
y <- xy[, p1]
if (xout) {
m <- cbind(x, y)
flag <- outfun(x, plotit = FALSE, ...)$keep
m <- m[flag, ]
x <- m[, 1:p]
y <- m[, p1]
}
x <- as.matrix(x)
init <- lsfit(x, y)
resid <- init$residuals
x1 <- cbind(1, x)
nu <- sqrt(1 - hat(x1))
low <- ncol(x) + 1
for (it in 1:iter) {
ev <- sort(abs(resid))
scale <- median(ev[c(low:length(y))])/qnorm(0.75)
rov <- (resid/scale)/nu
psi <- ifelse(abs(rov) <= bend, rov, bend * sign(rov))
wt <- nu * psi/(resid/scale)
new <- lsfit(x, y, wt)
if (max(abs(new$coef - init$coef)) < 1e-04)
break
init$coef <- new$coef
resid <- new$residuals
}
resid <- y - x1 %*% new$coef
if (max(abs(new$coef - init$coef)) >= 1e-04)
paste("failed to converge in", iter, "steps")
list(coef = new$coef, residuals = resid, w = wt)
}
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