Wrapper to built-in survival functions

Usage

surv(t, distPars, dist)

Arguments

t: double, time point where the survival is to be evaluated at.
distPars: Rcpp::List with distribution specific slots, see section ‘Details’.
dist: character name of the built-in distribution, see section ‘Details’.

Value

a double, giving the value of the survival function at time point t at the parameters' values.

Details

The function wraps all builtin-survival distributions. User can choose between the weibull, gamma, gengamma(generalized gamma) and burr (Burr type XII distribution). It is the user responsibility to pass the appropriate list of parameters as follows:

weibull: scale (the scale) and shape (the shape) parameters.
burr: scale (the scale) and shape1 (the shape1) and shape2 (the shape2) parameters.
gamma: scale (the scale) and shape (the shape) parameter.
gengamma: mu (location), sigma (scale) and Q (shape) parameters.

Examples

tt <- 2.5
## weibull

distP <- list(scale = 1.2, shape = 1.16)
alpha <- exp(-log(distP[["scale"]]) / distP[["shape"]])
pweibull(q = tt, scale = alpha, shape = distP[["shape"]],
                      lower.tail = FALSE)
#> [1] 0.03100227
surv(tt, distP, "weibull") ## (almost) same
#> [1] 0.03100227

## gamma
distP <- list(shape = 0.5, rate = 1.0 / 0.7)
pgamma(q = tt, rate = distP[["rate"]], shape = distP[["shape"]],
                    lower.tail = FALSE)
#> [1] 0.007526315
surv(tt, distP, "gamma")  ## (almost) same
#> [1] 0.007526315

## generalized gamma
distP <- list(mu = 0.5, sigma = 0.7, Q = 0.7)
flexsurv::pgengamma(q = tt, mu = distP[["mu"]],
                    sigma = distP[["sigma"]],
                    Q = distP[["Q"]],
                    lower.tail = FALSE)
#> [1] 0.1932044
surv(tt, distP, "gengamma")  ## (almost) same
#> [1] 0.002252019