Description Usage Arguments Details Value Author(s) See Also Examples
Make a mean-difference plot of two libraries of count data with smearing of points with very low counts, especially those that are zero for one of the columns.
1 2 |
object |
|
pair |
pair of experimental conditions to plot (if |
de.tags |
rownames for genes identified as being differentially expressed; use |
xlab |
x-label of plot |
ylab |
y-label of plot |
pch |
scalar or vector giving the character(s) to be used in the plot; default value of |
cex |
character expansion factor, numerical value giving the amount by which plotting text and symbols should be magnified relative to the default; default |
smearWidth |
width of the smear |
panel.first |
an expression to be evaluated after the plot axes are set up but before any plotting takes place; the default |
smooth.scatter |
logical, whether to produce a 'smooth scatter' plot using the |
lowess |
logical, indicating whether or not to add a lowess curve to the MA-plot to give an indication of any trend in the log-fold change with log-concentration |
... |
further arguments passed on to |
plotSmear
produces a type of mean-difference plot (or MA plot) with a special representation (smearing) of log-ratios that are infinite.
plotSmear
resolves the problem of plotting genes that have a total count of zero for one of the groups by adding the 'smear' of points at low A value.
The points to be smeared are identified as being equal to the minimum estimated concentration in one of the two groups.
The smear is created by using random uniform numbers of width smearWidth
to the left of the minimum A.
plotSmear
also allows easy highlighting of differentially expressed (DE) genes.
Invisibly returns the x and y coordinates of the plotted points, and a plot is created on the current device.
Mark Robinson created the original concept of smearing the infinite log-fold-changes.
1 2 3 4 5 6 7 8 9 10 11 12 | y <- matrix(rnbinom(10000,mu=5,size=2),ncol=4)
d <- DGEList(counts=y, group=rep(1:2,each=2), lib.size=colSums(y))
rownames(d$counts) <- paste("gene",1:nrow(d$counts),sep=".")
d <- estimateCommonDisp(d)
plotSmear(d)
# find differential expression
de <- exactTest(d)
# highlighting the top 500 most DE genes
de.genes <- rownames(topTags(de, n=500)$table)
plotSmear(d, de.tags=de.genes)
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Loading required package: limma
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