### Name: normalize.AffyBatch.vsn
### Title: Wrapper for vsn to be used as a normalization method in the
###   package affy
### Aliases: normalize.AffyBatch.vsn
### Keywords: robust

### ** Examples

### The example has been commented out because it takes a long time.
### Please also refer to the vignette.

## library(affy)
## library(affydata)
## data(Dilution)

### let affy know about vsn
## normalize.AffyBatch.methods <- c(normalize.AffyBatch.methods, "vsn")

## es1 = expresso(Dilution[1:2], 
##        bg.correct       = FALSE,   ## bg correction is done by vsn
##        normalize.method = "vsn",
##        pmcorrect.method = "pmonly", 
##        summary.method   = "medianpolish")

## es2 = expresso(Dilution[1:2], 
##        bgcorrect.method = "rma",
##        normalize.method = "quantiles", 
##        pmcorrect.method = "pmonly",
##        summary.method   = "medianpolish")

## par(mfrow=c(2,2), pch=".")

### extract expression values
## x1 = exprs(es1)
## x2 = exprs(es2) 
 
### scatter plot
## plot(x1, main="vsn: chip 3 vs 4")
## plot(x2, main="rma: chip 3 vs 4")

### rank(mean) - difference plot
## ylim = c(-0.7, 0.7)
## plot(rank(rowSums(x1)), diff(t(x1)), ylim=ylim, main="rank(mean) vs differences")
## abline(h=0, col="red")

## plot(rank(rowSums(x2)), diff(t(x2)), ylim=ylim, main="rank(mean) vs differences")
## abline(h=0, col="red")