[BioC] LimmaGUI Spot Quality

James Wettenhall wettenhall at wehi.edu.au
Fri Jul 2 17:41:52 CEST 2004


On Fri, 2 Jul 2004, Elizabeth Brooke-Powell wrote:
> adjust the model appropriately. I am not sure in this case that pretending
> to have GenePix will work as the numbers are not a simple 0 or 1 (good or

No, sorry I didn't mean to imply that you would be able to just 
use the GenePix option in limmaGUI as is.  I just thought it 
might by helpful for you to learn how weights can be defined 
(for _GenePix_ data), based on GenePix spot flags.  Notice that 
the weights we define for the GenePix flags are between 0 and 
1, just as your "quality weights" already are.  But after we 
process GenePix data, the number of _different_ values in the 
weights column would be small, e.g. in this weights vector: 
there are only three _different_ weight values (0, 0.1 and 1),
whereas for your data, the column of weights (between 0 and 1) 
could contain lots of different weight values between 0 and 1 
for the different genes.

I don't think you have told us the column name of this 
quality weight yet.  

Maybe you should ask the statistician who designed this 
quality weighting how he/she intended that it be used in  
normalization.  But it can probably be used directly in 
limma's normalization, and all you would have to do is tell us 
the appropriate column names which limma would need to read in 
for your data (Rf, Rb, Gf, Gb and Spot-Quality-Weighting) and 
then we can add an option to limma/limmaGUI to allow it to read 
in the appropriate columns for BlueFuse including the quality 

There are no plans at the moment to add a custom-dialog to 
limmaGUI for reading in an arbitrary column of weights from your 
raw image-analysis files.  But if you want to start combining 
the command-line interface with the GUI interface, you could 
read the weights into RG$weights in limmaGUIenvironment.  Then 
they would be automatically used for normalization.

(1) From the R console :
RG <- get("RG",envir=limmaGUIenvironment)
RG$weights <- ...

(2) From the "Evaluate R Code menu:
RG$weights <- ...

(In case (2), when using the "Evaluate R Code" menu, your R 
commands are automatically evaluated in limmaGUIenvironment 
which contains all of your microarray data objects used by 


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