Zero-inflated Poisson distribution
Probability mass function and random generation for the zero-inflated Poisson distribution.
dzip(x, lambda, pi, log = FALSE) pzip(q, lambda, pi, lower.tail = TRUE, log.p = FALSE) qzip(p, lambda, pi, lower.tail = TRUE, log.p = FALSE) rzip(n, lambda, pi)
x, q |
vector of quantiles. |
lambda |
vector of (non-negative) means. |
pi |
probability of extra zeros. |
log, log.p |
logical; if TRUE, probabilities p are given as log(p). |
lower.tail |
logical; if TRUE (default), probabilities are P[X ≤ x] otherwise, P[X > x]. |
p |
vector of probabilities. |
n |
number of observations. If |
Probability density function
f(x) = [if x = 0:] π + (1-π) * exp(-λ) [else:] (1-π) * dpois(x, lambda)
x <- rzip(1e5, 6, 0.33) xx <- -2:20 plot(prop.table(table(x)), type = "h") lines(xx, dzip(xx, 6, 0.33), col = "red") xx <- seq(0, 20, by = 0.01) plot(ecdf(x)) lines(xx, pzip(xx, 6, 0.33), col = "red")
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