stepfun(datax, datay=<<see below>>, type="left")
datax and
datay giving the locations of the jumps in the function. The values in
datax must be in increasing order.
type="left", the given points in
datax and
datay are at the left end of the level steps of the function; this gives a right-continuous function. If
type="right", the given points are at the right end of the level steps of the function; this gives a left-continuous function. Only the first character of the string is needed.
x and
y, described below. The return value from
stepfun is suitable for passing in to the functions
plot,
points, and
lines.
datax with all but one of the end values repeated.
datay.
When
type="left", each element of the input
datay is for the corresponding
datax element and the next
datax element. For
type="right", each element of
datay is for the corresponding
datax element and the previous
datax element.
The
type graphics parameter can be set to
"s" or
"S" to plot step functions. See the help file for
par for more details.
fit <- survfit(Surv(futime, fustat), data=ovarian) plot(stepfun(fit$time, fit$surv), type='l') # Add 95% confidence intervals. oldpar <- par(err=-1) # Avoid the "Lines out of bounds" messagges lines(stepfun(fit$time, exp(log(fit$surv) + 1.96*fit$std.err))) lines(stepfun(fit$time, exp(log(fit$surv) - 1.96*fit$std.err))) par(oldpar) # Turn graphics warnings back on