fsva: A function for performing frozen surrogate variable analysis...
In sva: Surrogate Variable Analysis

Description Usage Arguments Value Examples

This function performs frozen surrogate variable analysis as described in Parker, Corrada Bravo and Leek 2013. The approach uses a training database to create surrogate variables which are then used to remove batch effects both from the training database and a new data set for prediction purposes. For inferential analysis see sva, svaseq, with low level functionality available through irwsva.build and ssva.

1	fsva(dbdat, mod, sv, newdat = NULL, method = c("fast", "exact"))

`dbdat`	A m genes by n arrays matrix of expression data from the database/training data
`mod`	The model matrix for the terms included in the analysis for the training data
`sv`	The surrogate variable object created by running sva on dbdat using mod.
`newdat`	(optional) A set of test samples to be adjusted using the training database
`method`	If method ="fast" then the SVD is calculated using an online approach, this may introduce slight bias. If method="exact" the exact SVD is calculated, but will be slower

db An adjusted version of the training database where the effect of batch/expression heterogeneity has been removed

new An adjusted version of the new samples, adjusted one at a time using the fsva methodology.

newsv Surrogate variables for the new samples

library(bladderbatch)
library(pamr)
data(bladderdata)
dat <- bladderEset[1:50,]

pheno = pData(dat)
edata = exprs(dat)

set.seed(1234)
trainIndicator = sample(1:57,size=30,replace=FALSE)
testIndicator = (1:57)[-trainIndicator]
trainData = edata[,trainIndicator]
testData = edata[,testIndicator]
trainPheno = pheno[trainIndicator,]
testPheno = pheno[testIndicator,]

mydata = list(x=trainData,y=trainPheno$cancer)
mytrain = pamr.train(mydata)
table(pamr.predict(mytrain,testData,threshold=2),testPheno$cancer)

trainMod = model.matrix(~cancer,data=trainPheno)
trainMod0 = model.matrix(~1,data=trainPheno)
trainSv = sva(trainData,trainMod,trainMod0)

fsvaobj = fsva(trainData,trainMod,trainSv,testData)
mydataSv = list(x=fsvaobj$db,y=trainPheno$cancer)
mytrainSv = pamr.train(mydataSv)
table(pamr.predict(mytrainSv,fsvaobj$new,threshold=1),testPheno$cancer)