puma (version 3.12.0)

gmoExon: Compute gene and transcript expression values and standard deviatons from exon CEL Files

Description

This function converts an object of FeatureSet into an object of class exprReslt using the gamma model for exon chips. This function obtains confidence of measures, standard deviation and 5, 25, 50, 75 and 95 percentiles, as well as the estimated expression levels.

Usage

gmoExon( object ,exontype = c("Human", "Mouse", "Rat") ,background=FALSE ,gsnorm=c("median", "none", "mean", "meanlog") ,savepar=FALSE ,eps=1.0e-6 ,addConstant = 0 ,cl=NULL ,BatchFold=10
)

Arguments

object

an object of FeatureSet

exontype

character. specifying the type of exon chip.

background

Logical value. If TRUE, perform background correction before applying gmoExon.

gsnorm

character. specifying the algorithm of global scaling normalisation.

savepar

Logical value. If TRUE the estimated parameters of the model are saved in file par\_gmoExon.txt

eps

Optimisation termination criteria.

addConstant

numeric. This is an experimental feature and should not generally be changed from the default value.

cl

This function can be parallelised by setting parameter cl. For more details, please refer to the vignette.

BatchFold

we divide tasks into BatchFold*n jobs where n is the number of cluster nodes. The first n jobs are placed on the n nodes. When the first job is completed,the next job is placed on the available node. This continues until all jobs are completed. The default value is ten. The user also can change the value according to the number of cluster nodes n. We suggest that for bigger n BatchFold should be smaller.

Value

A list of two object of class exprReslt.

Details

The obtained expression measures are in log base 2 scale. Using the known relationships between genes, transcripts and probes, we propose a gamma model for exon array data to calculate transcript and gene expression levels. The algorithms of global scaling normalisation can be one of "median", "none", "mean", "meanlog". "mean" and "meanlog" are mean-centered normalisation on raw scale and log scale respectively, and "median" is median-centered normalisation. "none" will result in no global scaling normalisation being applied. This function can be parallelised by setting parameter cl. For more details, please refer to the vignette.

References

Liu,X., Milo,M., Lawrence,N.D. and Rattray,M. (2005) A tractable probabilistic model for Affymetrix probe-level analysis across multiple chips, Bioinformatics, 21:3637-3644.

Milo,M., Niranjan,M., Holley,M.C., Rattray,M. and Lawrence,N.D. (2004) A probabilistic approach for summarising oligonucleotide gene expression data, technical report available upon request.

Milo,M., Fazeli,A., Niranjan,M. and Lawrence,N.D. (2003) A probabilistic model for the extractioin of expression levels from oligonucleotide arrays, Biochemical Society Transactions, 31: 1510-1512.

Peter Spellucci. DONLP2 code and accompanying documentation. Electronically available via http://plato.la.asu.edu/donlp2.html

Risueno A, Fontanillo C, Dinger ME, De Las Rivas J. GATExplorer: genomic and transcriptomic explorer; mapping expression probes to gene loci, transcripts, exons and ncRNAs. BMC Bioinformatics.2010.

See Also

Related class exprReslt-class

Examples

## The following scripts show the use of the method.
## load CEL files
# celFiles<-c("SR20070419HEX01.CEL", "SR20070419HEX02.CEL","SR20070419HEX06.CEL","SR20070419HEX07.CEL)
#oligo_object.exon<-read.celfiles(celFiles);

## use method gmoExon to calculate the expression levels and related confidence 
## of the measures for the example data
#eset_gmoExon<-gmoExon(oligo_object.exon,exontype="Human",gsnorm="none",cl=cl)