[R] Is there dpois equivalent for zero-inflated Poisson?

[Matti Viljamaa]

I’m doing some optimisation that I first did with normal Poisson (only parameter theta was estimated), but now I’m doing the same with a zero-inflated Poisson model which
gives me two estimated parameters theta and p (p is also pi in some notation).

My question is, is there something equivalent to dpois that would use both of the parameters (or is the p parameter possibly unnecessary)?

I’m calculating the “fit” of the Poisson model

i.e. like

x = c(0,1,2,3,4,5,6)
y = c(3062,587,284,103,33,4,2)
fit1 <- sum(y)*dpois(x, est_theta)

and then comparing fit1 to the real observations.
	[[alternative HTML version deleted]]