Topic: Utilities

Topic Description:

Basic R utilities used in many packages and functions, such as date and string manipulations, statistical distributions, geometry of lines and distances. The R package date is required for the two data functions.

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File: utilities/distributions.r

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Function: dpois.max

Function Description: dpois.max

A probability distribution which is simply a curtailed poisson: all probability above a maximum integer, maxx, is given to that maximum. For all x

Function Arguments:

Argument	Default Value
x
lambda
maxx
log	FALSE

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Function Source:

dpois.max=function(x,lambda,maxx,log=FALSE)
{
result=standard=dpois(x,lambda=lambda)

below=which(x above=which(x>maxx)
exact=which(x==maxx)

if(length(below)>0) result[below]=standard[below]
if(length(above)>0) result[above]=0
if(length(exact)>0) result[exact]=1-sum(dpois(0:(maxx-1),lambda=lambda))

if(log) return(log(result))
else return(result)
}

#
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# dpois.trunc
#
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# A zero-truncated Poisson distribution.
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dpois.trunc=function(x,lambda,log=FALSE)
{
result=dpois(x,lambda=lambda)/(1-exp(-lambda))
zero=x==0
result[zero]=0

if(log) return(log(result))
else return(result)
}