[Bioc-devel] renameModelMatrixColumns mishap + patch for DESeq2

[Steve Lianoglou]

Greetings DESeq2ers,

I've been playing around with different ways to encode a 2x2 factorial
design I'm working with: 4 cell types, 4 treatments and exploring
what's cooking in there.

I thought that the nested interaction formula used in the limma user's
guide (section 8.5.3) would be an easy way to explore some obvious
questions since differential expression from different treatments
within each cell type (among other things) shake out quite cleanly
from the results of running the wald test since these end up as
columns in the design matrix, eg:

~ cell + cell:treatment

as long as the control treatment is the first level of the treatment
factor, we got columns for all cell:treatment effects, eg.
cellA:treatment1, cellA:treatment2, ..., cellD:treatment4)

Yay!

... almost ...

The problem is that the "renaming column" stuff in the fitNbinomGLMs
function seems to assume that we'll have columns for all main effects
in the design matrix, so the following line triggers an error:

modelMatrixNames[match(convertNames$from, modelMatrixNames)] <- convertNames$to

since you will find elements like "treatment2, ..., treatment4" among
the elements in `covertNames$from`. The call to match then returns NA
for these, and *boom*.

An easy fix would be to add the following line after the call to
`renameModelMatrixColumns`:

convertNames <- subset(convertNames, from %in% modelMatrixNames)

So the "if (renameCols)" block (line 1066 in core.R) now becomes:

  if (renameCols) {
    names(modelMatrixNames) <- modelMatrixNames
    convertNames <- renameModelMatrixColumns(modelMatrixNames,
                                             as.data.frame(colData(object)),
                                             modelFormula)
    convertNames <- subset(convertNames, from %in% modelMatrixNames)
    modelMatrixNames[match(convertNames$from, modelMatrixNames)] <-
convertNames$to
  }



--
Steve Lianoglou
Computational Biologist
Bioinformatics and Computational Biology
Genentech