EList: Expression List - class

Description Components Methods Author(s) See Also

Description

A list-based S4 classes for storing expression values (E-values) for a set of one-channel microarrays. EListRaw holds expression values on the raw scale. EList holds expression values on the log scale, usually after background correction and normalization. EListRaw objects are usually created by read.maimages. EList objects are usually created by normalizeBetweenArrays.

Components

EList objects can be created by new("EList",E) where E is a list. These classes contains no slots (other than .Data), but objects should contain a list component E as follows:

E numeric matrix containing expression values. Rows correspond to probes and columns to arrays. In an EListRaw object, these are unlogged values. In an EList object, these are log2 values.

Optional components include:

weights numeric matrix of same dimensions as E containing relative spot quality weights. Elements should be non-negative.
other list containing other matrices, all of the same dimensions as E.
genes data.frame containing probe information. Should have one row for each probe. May have any number of columns.
targets data.frame containing information on the target RNA samples. Rows correspond to arrays. May have any number of columns.

Valid EList or EListRaw objects may contain other optional components, but all probe or array information should be contained in the above components.

Methods

These classes inherit directly from class list so any operation appropriate for lists will work on objects of this class. In addition, EList objects can be subsetted and combined. EList objects will return dimensions and hence functions such as dim, nrow and ncol are defined. ELists also inherit a show method from the virtual class LargeDataObject, which means that ELists will print in a compact way.

Author(s)

Gordon Smyth

See Also

02.Classes gives an overview of all the classes defined by this package.

ExpressionSet is a more formal class in the Biobase package.


richierocks/limma2 documentation built on May 27, 2019, 8:47 a.m.