survival (version 2.35-3)

plot.survfit: Plot Method for 'survfit'

Description

A plot of survival curves is produced, one curve for each strata. The log=T option does extra work to avoid log(0), and to try to create a pleasing result. If there are zeros, they are plotted by default at 0.8 times the smallest non-zero value on the curve(s).

Usage

## S3 method for class 'survfit':
plot(x, conf.int=, mark.time=TRUE, 
 mark=3, col=1, lty=1, lwd=1, cex=1, log=FALSE, xscale=1, yscale=1,  
 firstx=0, firsty=1, xmax, ymin=0, fun, 
 xlab="", ylab="", xaxs="S", ...)

Arguments

x

an object of class survfit, usually returned by the survfit function.

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,

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. This is not treated as a vector; all marks have the same size.

log

a logical value, if TRUE the y axis wll be on a log scale. Alternately, one of the standard character strings "x", "y", or "xy" can be given to specific logarithmic horizontal and/or vertical axes.

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

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.

firstx, firsty

the starting point for the survival curves. If either of these is set to NA the plot will start at the first time point of the curve. By default, the plot program obeys tradition by having the plot start at (0,0).

If

xmax

the maximum horizontal plot coordinate. This can be used to shrink the range of a plot. It shortens the curve before plotting it, so that unlike using the xlim graphical parameter, warning messages about out of bounds points are

ymin

lower boundary for y values. Survival curves are most often drawn in the range of 0-1, even if none of the curves approach zero. The parameter is ignored if the fun argument is present, or if it has been set to NA.

fun

an arbitrary function defining a transformation of the survival curve. For example fun=log is an alternative way to draw a log-survival curve (but with the axis labeled with log(S) values), and fun=sqrt would gener

xlab

label given to the x-axis.

ylab

label given to the y-axis.

xaxs

either "S" for a survival curve or a standard x axis style as listed in par. Survival curves are usually displayed with the curve touching the y-axis, but not touching the bounding box of the plot on the other 3 sides

...

for future methods

Value

• a list with components x and y, containing the coordinates of the last point on each of the curves (but not the confidence limits). This may be useful for labeling.

Bugs

Survival curve objects created from a coxph model does not include the censoring times. Therefore, specifying mark.time=T does not work. 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) ~ x, data = aml) 
plot(leukemia.surv, lty = 2:3) 
legend(100, .9, c("Maintenance", "No Maintenance"), lty = 2:3) 
title("Kaplan-Meier Curves
for AML Maintenance Study") 
lsurv2 <- survfit(Surv(time, status) ~ x, aml, type='fleming') 
plot(lsurv2, lty=2:3, fun="cumhaz", 
	xlab="Months", ylab="Cumulative Hazard")