Displaying 4 results from an estimated 4 matches for "xfac".
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fac
2012 Jan 06
1
lme model specification problem (Error in MEEM...)
...als 12 21.176 1.765
# ... rest of output removed ...
I understand I can to some extent work around this limitation by
modifying the contrast encoding, but I then still don't get an overall
test for "as.factor(x)" (in the example above, a test for deviation from
linearity).
d$xfac <- factor(d$x)
contrasts(d$xfac)<-c(1,2,4,6)
summary(lme(y~xfac,random=~1|subj,data=d))
Is there a way to work around this limitation of lme? Or do I
mis-specify the model? Thanks for your advice.
Pascal
2001 Nov 21
2
distances from points to line
Dear all,
I have discovered that there are many things that I used to do in my GIS
which are easily done directly in R, for example calculating interpoint
distances using geoR and pick out points inside a polygon using splancs.
I now wonder, is there a function to create a line object like a
watercourse and then calculate the distances between many points in space
and this line?
I couldn't
2011 Jun 14
1
Expand DF with all levels of a variable
...ould like to expand a DF with all the missing levels of a variable.
a <- c(2,2,3,4,5,6,7,8,9)
a.cut <- cut(a, breaks=c(0,2,6,9,12), right=FALSE )
(x <- data.frame(a, a.cut))
# In 'x' the level "[0,2)" is "missing".
AddMissingLevel <- function(xdf) {
xfac <- factor( c("[0,2)", "[2,6)", "[6,9)", "[9,12)") )
xlevels <- levels(xfac)
if(length(xlevels) != nlevels(factor(xdf$a.cut))) {
v <- setdiff(xlevels, factor(xdf$a.cut))
u <- data.frame(a = 0, a.cut = v)
x <- r...
2012 Feb 08
2
need help with understanding coxph encoding
Hi, in coxph,
coxph(Surv(time, status)~x,data=alm).
How to encode x? For example, if x has two groups, the treatment group and
control group. if I encode them as 1 and 2. Is the HR results
treatment/control? What if I encode them as 0 and 1. I am confused with how
survival package works for HR. What should I do to get a treatment/control
HR?
Thank you.
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