PICS (version 2.16.0)

picsList-class: The pics class

Description

This object is used to gather all parameters from fitting PICS to multiple candidate regions (as returned by the `segmentReads' function). The objet contains the following slots: `List', `paraPrior', `paraEM', `minReads', `N', `Nc'. `List' is a list of `pics' or `picsError' objects. `paraPrior' is a list containing the hyperparameters used for the prior, `paraEM' is a list of convergence parameters for the EM, `minReads' is a list containing the minimum number of reads used to fit a region with `PICS', `N' is the total number of reads in the ChIP samples while `Nc' is the total number of reads in the control sample.

Arguments

object

An object of class pics.

Accessors

The PICS package provide accessors to directly access to most of the parameters/standard errors and chromosomes. In the code snippets below, `x' is a `picsList' object. For all accessors, the `picsError' objects are omitted, so that the accessors only return values for the `pics' objects (i.e. all valid binding events).

'chromosome(x)'

Gets the chromosome names of all candidate regions.

'mu(x)'

Gets the position estimates of all binding sites identified in all candidate regions.

'delta(x)'

Gets the average fragment lengths of all binding sites identified in all candidate regions.

'sigmaSqF(x)'

Gets the F peak variances of all binding sites identified in all candidate regions.

'sigmaSqR(x)'

Gets the R peak variances of all binding sites identified in all candidate regions.

'seF(x)'

Gets the standard errors of all binding site position estimates identified in all candidate regions.

'seF(x)'

Gets the standard errors of all F peak modes identified in all candidate regions.

'seR(x)'

Gets the standard errors of all R peak modes identified in all candidate regions.

'score(x)'

Gets the scores of all binding events identified in all candidate regions.

Constructor

newPicsList(List, paraEM, paraPrior, minReads, N, Nc)

List

The mixture weights (a vector)

paraEM

The binding site positions (a vector)

paraPrior

The DNA fragment lengths (a vector)

N

The variance parameters for the forward distribution (vector)

Nc

The variance parameters for the forward distribution (vector)

Methods

[

signature(x = ``pics''): subset PICS object.

Methods

length

signature(x = ``pics''): subset PICS object.

Constructor

newPicsList<-function(List, paraEM, paraPrior, minReads, N, Nc) constructs a new `picsList' object with the following arguments.

newPicsList

w

The mixture weights (a vector)

mu

The binding site positions (a vector)

delta

The DNA fragment lengths (a vector)

sigmaSqF

The variance parameters for the forward distribution (vector)

sigmaSqR

The variance parameters for the reverse distribution (vector)

seMu

The standard errors for mu (vector)

seMuF

The standard errors for muF (vector)

seMuR

The standard errors for muR (vector)

seMuR

The standard errors for muR (vector)

score

The scores for each binding event (vector)

Nmerged

The number of peaks that were merged (integer)

converge

A logical value, TRUE, if the EM as converged

infMat

The information matrix

chr

The chromosome for the region

References

X. Zhang, G. Robertson, M. Krzywinski, K. Ning, A. Droit, S. Jones, and R. Gottardo, ``PICS: Probabilistic Inference for ChIP-seq'' arXiv, 0903.3206, 2009. To appear in Biometrics.

See Also

pics

Examples

# Here is an example of how to construct such a region
# Typically, you would not do this manually, you would use the pics function to return a 'picsList' that contains a list of 'pics' or 'picsError' object.
w<-1
mu<-10000
delta<-150
sigmaSqF<-5000
sigmaSqR<-5000
seMu<-10
seMuF<-10
seMuR<-10
score<-5
Nmerged<-0
converge<-TRUE
infMat<-matrix(0)
chr<-"chr1"
range<-c(1000,2000)
# Contructor
#myPICS1<-newPics(w,mu,delta,sigmaSqF,sigmaSqR,seMu,seMuF,seMuR,score,Nmerged,converge,infMat,as.integer(range),chr)
#myPICS2<-newPics(w,mu+1000,delta,sigmaSqF,sigmaSqR,seMu,seMuF,seMuR,score,Nmerged,converge,infMat,as.integer(range),chr)

#minReads<-list(perPeak=2,perRegion=5)
#paraPrior<-list(xi=200,rho=1,alpha=20,beta=40000)
#paraEM<-list(minK=1,maxK=15,tol=10e-6,B=100)
#N<-100
#Nc<-200

#mynewPicsList<-newPicsList(list(myPICS1,myPICS2), paraEM, paraPrior, minReads, as.integer(100), as.integer(200))
# Accessors
# Get the standard error of Mu
#se(mynewPicsList)
# Get the standard error of MuF
#seF(mynewPicsList)
# Get the scores
#score(mynewPicsList)