Plot Method for survfit
USAGE: 
plot.survfit(survfit, conf.int=<<see below>>, mark.time=T, mark=3,
             col=1, lty=1, lwd=1, cex=1, log=F, yscale=1, xscale=1,
             xlab="", ylab="", xaxs='i', ...)
REQUIRED ARGUMENTS:
survfit:
an object of class survfit, usually returned by the survfit function.
OPTIONAL ARGUMENTS:
conf.int:
determines whether confidence intervals will be plotted. The default is to do so if there is only 1 curve, i.e., no strata.
mark.time:
controls the labeling of the curves. If set to FALSE, no labeling is done. If TRUE, then curves are marked at each censoring time which is not also a death time. If mark.time is a numeric vector, then curves are marked at the specified time points.
mark:
vector of mark parameters, which will be used to label the curves. The lines help file contains examples of the possible marks. The vector is reused cyclically if it is shorter than the number of curves.
col:
a vector of integers specifying colors for each curve. The default value is 1.
lty:
a vector of integers specifying line types for each curve. The default value is 1.
lwd:
a vector of numeric values for line widths. The default value is 1.
cex:
a numeric value specifying the size of the marks. Not a vector; all marks have the same size.
log:
a logical value, if TRUE the y axis wll be on a log scale.
yscale:
a numeric value used to multiply the labels on the y axis. A value of 100, for instance, would be used to give a percent scale. Only the labels are changed, not the actual plot coordinates, so that adding a curve with "lines(surv.exp(...))", say, will perform as it did without the yscale argument.
xscale:
a numeric value used like yscale for labels on the x axis. A value of 365.25 will give labels in years instead of the original days.
xlab:
label given to the x-axis.
ylab:
label given to the y-axis.
xaxs:
the x axis style, as listed in par. The default option of "r" leads to curves that are "too far" from the y axis. This is, of course, just a matter of aesthetic opinion.
VALUE:
a list with components x and y, containing the coordinates of the last point on each of the curves. This may be useful for labeling.
SIDE EFFECTS:
A plot of survival curves is produced, one curve for each strata.
BUGS:
Specifying mark.time = T does not work if survfit was created from a coxph model. In this case, censoring times are not marked on the curve(s). If you want to mark censoring times on the curve(s) resulting from a coxph fit, provide a vector of times as the mark.time argument in the call to plot.survfit or lines.survfit.
SEE ALSO:
par , survfit , lines.survfit .
EXAMPLES: 
leukemia.surv <- survfit(Surv(time, status) ~ group, data = leukemia)
plot(leukemia.surv, lty = 2:3)
legend(100, .9, c("Maintenance", "No Maintenance"), lty = 2:3)
title("Kaplan-Meier Curves0or AML Maintenance Study")