[R] Extracting values from Surv function in survival package

[Dennis Fisher]

OS X
R 4.3.3

Colleagues

I have created objects using the Surv function in the survival package:
> FIT.1
Call: survfit(formula = FORMULA1)

                                       n events median 0.95LCL 0.95UCL
SUBDATA$ARM=1, SUBDATA[, EXP.STRAT]=0 18     13    345     156      NA
SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=1 13      5     NA     186      NA
SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=2  5      5    168      81      NA
SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=3  1      1     22      NA      NA

I am interested in extracting the “n” and “events” values.
“n” is easy:
> FIT.1[[1]]
[1] 18 13  5  1

or
> FIT.1$n
[1] 18 13  5  1

But I can’t figure out how to access “events”.

str(FIT.1) provides no insights:
List of 17
 $ n        : int [1:4] 18 13 5 1
 $ time     : num [1:37] 45 106 107 124 152 156 170 176 319 371 ...
 $ n.risk   : num [1:37] 18 17 16 15 14 13 12 11 10 9 ...
 $ n.event  : num [1:37] 1 1 1 1 1 1 1 1 1 1 ...
 $ n.censor : num [1:37] 0 0 0 0 0 0 0 0 0 0 ...
 $ surv     : num [1:37] 0.944 0.889 0.833 0.778 0.722 ...
 $ std.err  : num [1:37] 0.0572 0.0833 0.1054 0.126 0.1462 ...
 $ cumhaz   : num [1:37] 0.0556 0.1144 0.1769 0.2435 0.315 ...
 $ std.chaz : num [1:37] 0.0556 0.0809 0.1022 0.1221 0.1414 ...
 $ strata   : Named int [1:4] 18 13 5 1
  ..- attr(*, "names")= chr [1:4] "SUBDATA$ARM=1, SUBDATA[, EXP.STRAT]=0" "SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=1" "SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=2" "SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=3"
 $ type     : chr "right"
 $ logse    : logi TRUE
 $ conf.int : num 0.95
 $ conf.type: chr "log"
 $ lower    : num [1:37] 0.844 0.755 0.678 0.608 0.542 ...
 $ upper    : num [1:37] 1 1 1 0.996 0.962 ...
 $ call     : language survfit(formula = FORMULA1)
 - attr(*, "class")= chr "survfit"

If I could access:
                                       n events median 0.95LCL 0.95UCL
SUBDATA$ARM=1, SUBDATA[, EXP.STRAT]=0 18     13    345     156      NA
SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=1 13      5     NA     186      NA
SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=2  5      5    168      81      NA
SUBDATA$ARM=2, SUBDATA[, EXP.STRAT]=3  1      1     22      NA      NA
it should be easy to get “events”.

Any thoughts?

Dennis

Dennis Fisher MD
P < (The "P Less Than" Company)
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