unfold: Stereological unfolding

Description

Unfolding the (joint) distribution of planar parameters

Usage

unfold(sp, nclass, maxIt = 64, nCores = getOption("par.unfoldr", 1), ...)

Arguments

section profiles

nclass

number of classes

maxIt

maximum number of EM iterations

nCores

number of cpu cores used

...

optional arguments passed to setbreaks

Value

object of class unfold

Details

This is a S3 method for either trivariate stereological unfolding or estimation of 3d diameter distribution of spheres (Wicksell's corpuscle problem). The function aggregates all intermediate calculation steps required for the unfolding procedure given the data in the prescribed format and returning the parameters as count data in histogram form. The section profiles object sp, see sectionProfiles, is either of class prolate or oblate for the reconstruction of spheroids or in case of spheres the sp is simply a numeric vector of circle diameters. Here, the class of section profiles corresponds to the type of objects that will be reconstructed. The number of bin classes is set by the argument nclass which is either a scalar value in case of Wicksell's corpuscle problem or a vector of length three defined in the order of the number of size, angle and shape class limits. Using multiple cpu cores during the calculations is controlled by either setting the option 'par.unfoldr' to a user chosen amount of cores or by the argument nCores directly. The return value of the function is an object of class unfold whose arguments are as follows

{ (trivariate) histogram of section profile parameters} N_V{ (trivariate) histogram of reconstructed parameters} P{ array of coefficients} breaks{ list of class limits for binning the parameter values}

Examples

Run this code

data(spheroids)
## set number of cpu cores (optional)
# options(par.unfoldr=8)

## Setup spheroid system 
setupSpheroidSystem(spheroids,box=list(c(0,5)))

## unfolding
sp <- verticalSection(spheroids,2.5)
ret <- unfold(sp,c(10,9,8),kap=1.3)