The Poisson Distribution, Using Multiple Draws

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

Usage

dpois_rvec(x, lambda, log = FALSE)

ppois_rvec(q, lambda, lower.tail = TRUE, log.p = FALSE)

qpois_rvec(p, lambda, lower.tail = TRUE, log.p = FALSE)

rpois_rvec(n, lambda, n_draw = NULL)

Arguments

x: Quantiles. Can be an rvec.
lambda: Vector of means. See stats::rpois(). 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.
rpois_rvec() always returns doubles (not integers).

Details

Functions dpois_rvec(), ppois_rvec(), ppois_rvec() and rpois_rvec() work like base R functions dpois(), ppois(), qpois(), and rpois(), except that they accept rvecs as inputs. If any input is an rvec, then the output will be too. Function rpois_rvec() also returns an rvec if a value for n_draw is supplied.

dpois_rvec(), ppois_rvec(), ppois_rvec() and rpois_rvec() use tidyverse vector recycling rules:

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

Warning

From version rvec version 0.7.4 onwards, rpois_rvec() always returns doubles (not integers).

Examples

x <- rvec(list(c(3, 5),
               c(1, 2)))
dpois_rvec(x, lambda = 3)
#> <rvec_dbl<2>[2]>
#> [1] 0.224,0.1008 0.1494,0.224
ppois_rvec(x, lambda = 3)
#> <rvec_dbl<2>[2]>
#> [1] 0.6472,0.9161 0.1991,0.4232

rpois_rvec(n = 2,
           lambda = c(5, 10),
           n_draw = 1000)
#> <rvec_dbl<1000>[2]>
#> [1] 5 (1, 10)  10 (4, 16)