On 08/08/2017 03:59 AM, Angerer, Philipp wrote:

Hi Aaron,

I guess this would be a question for the SummarizedExperiment developers, 
though personally, I never liked ExpressionSet's inclination to slap names on 

Too bad we’re bound to SummarizedExperiment’s “rows” and “cols”. Since they 
always refer to features and samples, respectively: Why not name them that?

There’s already too many APIs in too many programming languages that 
confusingly have one or the other convention – if whe know which is which, why 
not name them after that knowledge?

It probably wouldn't be a good idea to store distances as expression matrices. 
However, if there is a need for it, we can add a new slot for distance 
matrices. I think SC3 has a similar requirement, so perhaps this would be more 
generally useful than I first thought. You can post an issue on the github 
repository to remind Davide or me to do it.

Distance matrices (cell×cell) can’t only come from cell×gene matrices. You can 
e.g. use dynamic time warping to create them from cell×gene×time arrays.

Finally, I'm not sure what advantages those ergonomics provide. Indeed, if 
every package defines its own plot() S4 method for SingleCellExperiment, they 
will clobber each other in the dispatch table, resulting in some interesting 
results dependent on package loading order. If you have destiny-specific data 
and methods, best to keep them separate rather than stuffing them into the SCE 

I wrote that I could e.g. create a plot_dm method, which plots a diffusion map 
stored in a SCE.

Also I didn’t mean the plot method with ergonomics. I meant fortify , names , $ 
, and [[ . Those would be very useful, as you could just do things like the 
following, and have autocompletion:
sce$Predicate1 <- sce$SampleMeta1 > 40 # `$` accesses counts (by gene) and 
rowData. `$<-` sets rowData
qplot(Gene1, Gene2, colour = Predicate1, data = sce) # fortify creates a 
data.frame containing cbind(t(counts), rowData)

FWIW, SummarizedExperiment (hence SingleCellExperimet) uses $ (and $<-; also [[ and [[<-) to access (with auto-completion) colData. And it wouldn't be a good idea to have $ access one element (counts) and $<- modify another (rowData), or to mix what $ and [[ access.


Just as you can do now with DiffusionMap objects.

Also I’m not sure if i got rowData and the “t” right in the above code ;) I 
meant cbind(counts as cell×gene, sampleMeta as cell×n_meta)


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