The Gamma Distribution, Using Multiple Draws

Density, distribution function, quantile function and random generation for the gamma distribution, modified to work with rvecs.

Usage

dgamma_rvec(x, shape, rate = 1, scale = 1/rate, log = FALSE)

pgamma_rvec(
  q,
  shape,
  rate = 1,
  scale = 1/rate,
  lower.tail = TRUE,
  log.p = FALSE
)

qgamma_rvec(
  p,
  shape,
  rate = 1,
  scale = 1/rate,
  lower.tail = TRUE,
  log.p = FALSE
)

rgamma_rvec(n, shape, rate = 1, scale = 1/rate, n_draw = NULL)

Arguments

x: Quantiles. Can be an rvec.
shape: Shape parameter. See stats::dgamma(). Can be an rvec.
rate: Rate parameter. See stats::dgamma(). Can be an rvec.
scale: Scale parameter. An alterative to rate. See stats::dgamma(). Can be an rvec.
log, log.p: Whether to return results on a log scale. Default is FALSE. Cannot be an rvec.
q: Quantiles. Can be an rvec.
lower.tail: Whether to return \(P[X \le x]\), as opposed to \(P[X > x]\). Default is TRUE. Cannot be an rvec.
p: Probabilities. Can be an rvec.
n: The length of random vector being created. Cannot be an rvec.
n_draw: Number of random draws in the random vector being created. Cannot be an rvec.

Value

If any of the arguments are rvecs, or if a value for n_draw is supplied, then an rvec
Otherwise an ordinary R vector.

Details

Functions dgamma_rvec(), pgamma_rvec(), pgamma_rvec() and rgamma_rvec() work like base R functions dgamma(), pgamma(), qgamma(), and rgamma(), except that they accept rvecs as inputs. If any input is an rvec, then the output will be too. Function rgamma_rvec() also returns an rvec if a value for n_draw is supplied.

dgamma_rvec(), pgamma_rvec(), pgamma_rvec() and rgamma_rvec() use tidyverse vector recycling rules:

Vectors of length 1 are recycled
All other vectors must have the same size

Examples

x <- rvec(list(c(3, 5.1),
               c(0.1, 2.3)))
dgamma_rvec(x, shape = 1)
#> <rvec_dbl<2>[2]>
#> [1] 0.04979,0.006097 0.9048,0.1003   
pgamma_rvec(x, shape = 1)
#> <rvec_dbl<2>[2]>
#> [1] 0.9502,0.9939  0.09516,0.8997

rgamma_rvec(n = 2,
            shape = 1,
            rate = c(0.5, 1),
            n_draw = 1000)
#> <rvec_dbl<1000>[2]>
#> [1] 1.3 (0.051, 7.9)  0.68 (0.023, 3.5)