picsList-class {PICS} | R Documentation

## 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

### Author(s)

Xuekui Zhang, Arnaud Droit <arnaud.droit@crchuq.ualaval.ca> and Raphael Gottardo <rgottard@fhcrc.org>

### 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)

[Package PICS version 2.28.0 Index]