Convert the survival fit data into a data frame designed for plotting
within g_km.
This starts from the broom::tidy() result, and then:
- post-processes the - stratacolumn into a factor,
- extends each stratum by an additional first row with time 0 and probability 1 so that downstream plot lines start at those coordinates, 
- adds a - censorcolumn,
- filters the rows before - max_time.
Arguments
- fit_km
- ( - survfit)
 result of- survival::survfit().
- armval
- ( - string)
 used as strata name when treatment arm variable only has one level. Default is "All".
- max_time
- ( - numeric)
 maximum value to show on X axis. Only data values less than or up to this threshold value will be plotted (defaults to- NULL).
Examples
if (FALSE) {
library(dplyr)
library(survival)
# Test with multiple arms
tern_ex_adtte %>%
  filter(PARAMCD == "OS") %>%
  survfit(form = Surv(AVAL, 1 - CNSR) ~ ARMCD, data = .) %>%
  h_data_plot()
# Test with single arm
tern_ex_adtte %>%
  filter(PARAMCD == "OS", ARMCD == "ARM B") %>%
  survfit(form = Surv(AVAL, 1 - CNSR) ~ ARMCD, data = .) %>%
  h_data_plot(armval = "ARM B")
}