[R] I have a problem

[David Winsemius]

On Jul 31, 2010, at 6:29 AM, 笑啸 wrote:

> dear£º
>   in  the  example£¨nomogram£©£¬I don't understand the meanings  
> of the program which have been  marked by red line.

This is a plain text mailing list, hence no red line ... in fact no  
line at all. Use some other device such also outlining with (text)  
comment lines such as:

#---need explanation for code starting here-----
R code
# ---end----

And. Read the Posting Guide. You have just quoted verbatim from the  
nomogram help page in the rms package.

-- 
David.


> And how to compile the program(L <- .4*(sex=='male') + .045*(age-50) +
> (log(cholesterol - 10)-5.2)*(-2*(sex=='female') + 2*(sex=='male'))).
>
>
> n <- 1000 # define sample size
> set.seed(17) # so can reproduce the results
> age <- rnorm(n, 50, 10)
> blood.pressure <- rnorm(n, 120, 15)
> cholesterol <- rnorm(n, 200, 25)
> sex <- factor(sample(c('female','male'), n,TRUE))
> # Specify population model for log odds that Y=1
> L <- .4*(sex=='male') + .045*(age-50) +
> (log(cholesterol - 10)-5.2)*(-2*(sex=='female') + 2*(sex=='male'))
> # Simulate binary y to have Prob(y=1) = 1/[1+exp(-L)]
> y <- ifelse(runif(n) < plogis(L), 1, 0)
> ddist <- datadist(age, blood.pressure, cholesterol, sex)
> options(datadist='ddist')
> f <- lrm(y ~ lsp(age,50)+sex*rcs(cholesterol,4)+blood.pressure)
> nom <- nomogram(f, fun=function(x)1/(1+exp(-x)), # or fun=plogis
> fun.at=c(.001,.01,.05,seq(.1,.9,by=.1),.95,.99,.999),
> funlabel="Risk of Death")
> #Instead of fun.at, could have specified fun.lp.at=logit of
> ...
> Thank you for you expain !
>                                                                                truly 
>  yours
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT