zigeom: Zero-inflated geometric distribution

In RTMBdist: Distributions Compatible with Automatic Differentiation by 'RTMB'

Zero-inflated geometric distribution

Description

Probability mass function, distribution function, and random generation for the zero-inflated geometric distribution.

Usage

dzigeom(x, prob, zeroprob = 0, log = FALSE)

pzigeom(q, prob, zeroprob = 0, lower.tail = TRUE, log.p = FALSE)

rzigeom(n, prob, zeroprob = 0)

Arguments

x, q	integer vector of counts
prob	probability of success in each trial, in (0,1]
zeroprob	zero-inflation probability between 0 and 1
log, log.p	logical; return log-density if TRUE
lower.tail	logical; if TRUE, probabilities are P[X \le x], otherwise, P[X > x].
n	number of random values to return.

Details

This implementation allows for automatic differentiation with RTMB.

P(X=k;\,\pi,p_0) = p_0\,\mathbf{1}[k=0] + (1-p_0)\,P_{\mathrm{Geom}}(k;\,\pi),

where p_0 is zeroprob. The zeros are a mixture of structural zeros and zeros generated by the geometric itself, so zeroprob is not the probability of observing a zero; see hgeom for the hurdle version, where it is.

Value

dzigeom gives the probability mass function, pzigeom gives the distribution function, and rzigeom generates random deviates.

See Also

ztgeom, hgeom, zinbinom, zipois

Examples

set.seed(123)
x <- rzigeom(5, prob = 0.3, zeroprob = 0.4)
d <- dzigeom(x, prob = 0.3, zeroprob = 0.4)
p <- pzigeom(x, prob = 0.3, zeroprob = 0.4)

RTMBdist documentation built on Oct. 31, 2026, 5:07 p.m.