picsList-class {PICS} | R Documentation |
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.
object |
An object of class |
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).
Gets the chromosome names of all candidate regions.
Gets the position estimates of all binding sites identified in all candidate regions.
Gets the average fragment lengths of all binding sites identified in all candidate regions.
Gets the F peak variances of all binding sites identified in all candidate regions.
Gets the R peak variances of all binding sites identified in all candidate regions.
Gets the standard errors of all binding site position estimates identified in all candidate regions.
Gets the standard errors of all F peak modes identified in all candidate regions.
Gets the standard errors of all R peak modes identified in all candidate regions.
Gets the scores of all binding events identified in all candidate regions.
newPicsList(List, paraEM, paraPrior, minReads, N, Nc)
The mixture weights (a vector)
The binding site positions (a vector)
The DNA fragment lengths (a vector)
The variance parameters for the forward distribution (vector)
The variance parameters for the forward distribution (vector)
signature(x = ``pics'')
: subset PICS object.
signature(x = ``pics'')
: subset PICS object.
newPicsList<-function(List, paraEM, paraPrior, minReads, N, Nc) constructs a new ‘picsList’ object with the following arguments.
The mixture weights (a vector)
The binding site positions (a vector)
The DNA fragment lengths (a vector)
The variance parameters for the forward distribution (vector)
The variance parameters for the reverse distribution (vector)
The standard errors for mu (vector)
The standard errors for muF (vector)
The standard errors for muR (vector)
The standard errors for muR (vector)
The scores for each binding event (vector)
The number of peaks that were merged (integer)
A logical value, TRUE, if the EM as converged
The information matrix
The chromosome for the region
Xuekui Zhang, Arnaud Droit <arnaud.droit@crchuq.ualaval.ca> and Raphael Gottardo <rgottard@fhcrc.org>
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.
# 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)