[Bioc-devel] RFC: xy2i and i2xy in *cdf packages

[Henrik Bengtsson]

Hi,

may I suggest to leave the package framework for "CDF package" an move
to an object-oriented framework.  Define a class AffyCdf class that
provide various access methods, e.g. indexToCoordinate() and
coordinateToIndex().  Let subclass AffyCdfPackage extend AffyCdf such
that its methods queries existing CDF package. Yet another class
AffyCdfFile works directly towards CDF files.  AffyCdfDb works towards
a data base, and so on.  All provide the same API.

Migration: First step would be add an object of class AffyCdfPackage
inside CDF packages, alternatively provide an additional way of
loading CDF packages, such that there is an object, say with the same
name as the "clean" chip type (CDF) name, e.g. 'hgu133a'.
Then packages start using the AffyCdfPackage API (instead of accessing
the CDF package environment directly), e.g. cdf <- hgu133a; idx <-
coordinateToIndex(cdf, xy).  Both CDF package and AffyCdf object
coexists for the price of one until all packages migrated.  When that
is done, we have much more flexibility.

With the above design it would be a piece of a cake to add a
AffyCdfFile class to query CDF files on the fly using affxparser.

/Henrik


On 3/26/07, Wolfgang Huber <huber at ebi.ac.uk> wrote:
> Hi Jim,
>
> I think Francesco's point is valid.
> The chip design is independent of particular instances of data, and
> includes the size of the chip. That the chip size resides in the data
> container (AffyBatch) and all the other geometry annotation in the CDF
> is incoherent. So, when the i2xy and xy2i functions go, can't we have
> this annotation constant defined in the CDF package as well, so that you
> can say, for example
>
>   xy <- indices2xy(i, cdf=hgu133acdf)
>
> Btw, the reason for putting the xy2i and i2xy functions into the CDF
> packages was that these mapping functions are really a chip-geometry
> annotation. It was a mistake to export them like that, though, they
> should always only have been visible as hgu133acdf::xy2i() or
> hgu133acdf$xy2i().
>
>   Best wishes
>   Wolfgang
>
>
> > Hi Francesco,
> >
> > Francesco Ferrari wrote:
> >> PS: I know that no package uses these functions, but we use them to
> >> produce data for another package (work is still in progress). We could
> >> use indices2xy() and xy2indices() functions from affy package, but the
> >> value for "nr" parameter is required.
> >
> > I'm confused by this. What does your package do with a cdf package that
> > doesn't explicitly involve an AffyBatch?
> >
> > Best,
> >
> > Jim
>
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