[R] legend

[David Winsemius]

On Sep 22, 2010, at 1:39 PM, threshold wrote:

>
> Hi,
> there is a function to plot survival curves:
>
> library(survival)
> plot.KM <- function(survival, x, x_cut.off, main='', label='')
> {
> plot(survfit(survival ~ I(x >= x_cut.off)), main=main)
> legend('bottomleft', c(expression(label >=  
> x_cut.off),expression(label <
> x_cut.off)))
> }

This is untested because "survival" is not an object for the rest of  
us to survfit:

plot.KM <- function(survival, x, x_cut.off, main='', label='')
{
#really kind of worried about whether this part will work, but perhaps  
you already have this running?
plot(survfit(survival ~ I(x >= x_cut.off)), main=main)
#####
## perhaps something like this ... untested d/t no data example
legend('bottomleft',
        labels= bquote( .(label)>=.(x_cut.off),
                        .(label)<.(x_cut.off) ) )
}

(And if you have made such a Surv object, perhaps naming it something  
other than the package name would be less confusing to us ordinary  
mortals.)

-- David.



>
> Now, I need to determine as the argument what appears in the legend.  
> I want
> plot.KM(survival, x, x_cut.off=0.5, main='', label='ABC')
> but what I get is ('label < x_cut.off') in legend instead of  
> 'ABC<0.5'.
> Symbol '>=' should be in mathematical form. will appreciate any help.
>
> robert
>
>
> -- 
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>
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David Winsemius, MD
West Hartford, CT