A second dataset is the Mayo Clinic Lung Cancer data, available from
the survival
package. We can make it available for
Rattle using the data command or directly within
Rattle using the Library option of the Data
tab. The target (in Rattle's terms, though usually referred to as the
time variable) is the variable time and the risk (again
in Rattle's terms, though usually referred to as the event or status
indicator) is the status:
> data(lung)
> names(lung)
|
[1] "inst" "time" "status" "age"
[5] "sex" "ph.ecog" "ph.karno" "pat.karno"
[9] "meal.cal" "wt.loss"
|
A sipmle plot.
with(lung, plot(age, time, pch=status, col=status+1))
legend("topleft", c("alive", "dead"), pch=1:2, col=2:3)
We create a survival object using the Surv function.
> l.Surv <- with(lung, Surv(time, status))
> head(lung[2:3])
|
time status
1 306 2
2 455 2
3 1010 1
4 210 2
5 883 2
6 1022 1
|
[1] 306 455 1010+ 210 883 1022+
|
time status
[1,] 306 1
[2,] 455 1
[3,] 1010 0
[4,] 210 1
[5,] 883 1
[6,] 1022 0
|
Again, those observations of entities that are still alive are marked
with a + when printed. Internally we can see the survival
object is storing the information in a matrix.
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