[Bioc-devel] Problem with S4 method dispatch: method found for SummarizedExperiment, but not SingleCellExperiment
Helena L. Crowell
he|en@ @end|ng |rom crowe||@eu
Wed Jan 8 13:41:05 CET 2025
SCE inherits from SE, but not vice versa. So setting the class union on SCE (not SE) will do the trick. Briefly, Anything defined on an SCE will work upstream (SE), but anything defined on SE will not work downstream (SPE, SCE).
***
This works:
library("Matrix")
library("Biobase")
library("SummarizedExperiment")
library("SingleCellExperiment")
setClassUnion("ExpData", c("matrix", "dgCMatrix",
"ExpressionSet", "SingleCellExperiment"))
setGeneric("expShow", \(.) standardGeneric("expShow"))
setMethod("expShow", "ExpData", \(.) show(.))
p <- 10
n <- 30
y <- matrix(rnorm(n*p), nrow=p, ncol=n,
dimnames=list(
paste("g", 1:p, sep="") ,
paste("s", 1:n, sep="")))
se <- SummarizedExperiment(y)
sce <- SingleCellExperiment(y)
expShow(se)
expShow(sce)
> On Jan 7, 2025, at 21:33, Axel Klenk <axel.klenk using gmail.com> wrote:
>
> Dear Community, dear S4 Experts,
>
> in the GSVA package I want to use an S4 class union as a superclass
> for all supported data containers and S4 methods
> defined for this superclass, rather than for each subclass, where a
> class-specific implementation is not necessary. In particular
> I want to avoid having to implement individual methods for all current
> (and possibly, future) subclasses of SummarizedExperiment
> for common operations like accessing assay names and dimensions, assay
> data, etc.
>
> As you can see from the example code and output below, this works as
> expected for SummarizedExperiment objects but not
> for its subclasses such as SingleCellExperiment or SpatialExperiment
> (if SummarizedExperiment is part of the class union and
> the others are not). In the latter case the result is "Error: unable
> to find an inherited method for function ..." (please see below).
>
> I'd be very grateful if someone with more S4 expertise than myself
> could please let me know if and how this can be solved -- or
> if the whole thing is not a good idea at all. ;-)
>
> Thanks a lot,
>
> - axel
>
>
>
> ### define a class union as a common superclass
> library("Matrix")
> library("Biobase")
> library("SummarizedExperiment")
> library("SingleCellExperiment")
> ## [package startup messages omitted]
>
> setClassUnion("ExpData",
> c("matrix", "dgCMatrix", "ExpressionSet", "SummarizedExperiment"))
>
> ### ... and an example method for the superclass
> setGeneric("expShow", function(object) standardGeneric("expShow"))
> setMethod("expShow",
> signature=signature(object="ExpData"),
> function(object) {
> show(object)
> })
>
> ### generate some example data and test the method:
> p <- 10
> n <- 30
> y <- matrix(rnorm(n*p), nrow=p, ncol=n,
> dimnames=list(paste("g", 1:p, sep="") , paste("s", 1:n, sep="")))
>
> se <- SummarizedExperiment(y)
> show(se)
> ## class: SummarizedExperiment
> ## dim: 10 30
> ## metadata(0):
> ## assays(1): ''
> ## rownames(10): g1 g2 ... g9 g10
> ## rowData names(0):
> ## colnames(30): s1 s2 ... s29 s30
> ## colData names(0):
>
> expShow(se)
> ## class: SummarizedExperiment
> ## dim: 10 30
> ## metadata(0):
> ## assays(1): ''
> ## rownames(10): g1 g2 ... g9 g10
> ## rowData names(0):
> ## colnames(30): s1 s2 ... s29 s30
> ## colData names(0):
>
> sce <- SingleCellExperiment(y)
> show(sce)
> ## class: SingleCellExperiment
> ## dim: 10 30
> ## metadata(0):
> ## assays(1): ''
> ## rownames(10): g1 g2 ... g9 g10
> ## rowData names(0):
> ## colnames(30): s1 s2 ... s29 s30
> ## colData names(0):
> ## reducedDimNames(0):
> ## mainExpName: NULL
> ## altExpNames(0):
>
> expShow(sce)
> ## Error: unable to find an inherited method for function 'expShow'
> for signature 'object = "SingleCellExperiment"'
>
> ### ### ###
>
> ## we can define a new subclass of SummarizedExperiment in the global
> environment that works -- as
> ## long as it is not coerced to SingleCellExperiment
>
> setClass("expA",
> contains="RangedSummarizedExperiment")
>
> ea <- new("expA")
> show(ea)
> ## An object of class "expA"
> ## Slot "rowRanges":
> ## GRanges object with 0 ranges and 0 metadata columns:
> ## seqnames ranges strand
> ## <Rle> <IRanges> <Rle>
> ## -------
> ## seqinfo: no sequences
> ##
> ## Slot "colData":
> ## DataFrame with 0 rows and 0 columns
> ##
> ## Slot "assays":
> ## NULL
> ##
> ## Slot "NAMES":
> ## NULL
> ##
> ## Slot "elementMetadata":
> ## DataFrame with 0 rows and 0 columns
> ##
> ## Slot "metadata":
> ## list()
>
> expShow(ea)
> ## class: SummarizedExperiment
> ## dim: 0 0
> ## metadata(0):
> ## assays(0):
> ## rownames: NULL
> ## rowData names(0):
> ## colnames: NULL
> ## colData names(0):
>
> scea <- as(ea, "SingleCellExperiment")
> show(scea)
> ## class: SingleCellExperiment
> ## dim: 0 0
> ## metadata(0):
> ## assays(0):
> ## rownames: NULL
> ## rowData names(0):
> ## colnames: NULL
> ## colData names(0):
> ## reducedDimNames(0):
> ## mainExpName: NULL
> ## altExpNames(0):
>
> expShow(scea)
> ## Error: unable to find an inherited method for function 'expShow'
> for signature 'object = "SingleCellExperiment"'
>
> ### ### ### ### ###
>
> ## as shown below, SummarizedExperiment and ExpData "know" about their
> inheritance relation but
> ## SingleCellExperiment does not...
>
> getClass("SummarizedExperiment")
> ## Class "SummarizedExperiment" [package "SummarizedExperiment"]
> ##
> ## Slots:
> ##
> ## Name: colData assays NAMES
> elementMetadata metadata
> ## Class: DataFrame Assays_OR_NULL character_OR_NULL
> DataFrame list
> ##
> ## Extends:
> ## Class "RectangularData", directly
> ## Class "Vector", directly
> ## Class "ExpData", directly
> ## Class "Annotated", by class "Vector", distance 2
> ## Class "vector_OR_Vector", by class "Vector", distance 2
> ##
> ## Known Subclasses:
> ## Class "RangedSummarizedExperiment", directly, with explicit coerce
>
> getClass("ExpData")
> ## Extended class definition ( "ClassUnionRepresentation" )
> ## Virtual Class "ExpData" [in ".GlobalEnv"]
> ##
> ## No Slots, prototype of class "matrix"
> ##
> ## Known Subclasses:
> ## Class "matrix", directly
> ## Class "dgCMatrix", directly
> ## Class "ExpressionSet", directly
> ## Class "SummarizedExperiment", directly
> ## Class "mts", by class "matrix", distance 2
> ## Class "RangedSummarizedExperiment", by class
> "SummarizedExperiment", distance 2, with explicit coerce
>
> getClass("SingleCellExperiment")
> ## Class "SingleCellExperiment" [package "SingleCellExperiment"]
> ##
> ## Slots:
> ##
> ## Name: int_elementMetadata int_colData
> int_metadata
> ## Class: DataFrame DataFrame
> list
> ##
> ## Name: rowRanges colData
> assays
> ## Class: GenomicRanges_OR_GRangesList DataFrame
> Assays_OR_NULL
> ##
> ## Name: NAMES elementMetadata
> metadata
> ## Class: character_OR_NULL DataFrame
> list
> ##
> ## Extends:
> ## Class "RangedSummarizedExperiment", directly
> ## Class "SummarizedExperiment", by class
> "RangedSummarizedExperiment", distance 2
> ## Class "RectangularData", by class "RangedSummarizedExperiment", distance 3
> ## Class "Vector", by class "RangedSummarizedExperiment", distance 3
> ## Class "Annotated", by class "RangedSummarizedExperiment", distance 4
> ## Class "vector_OR_Vector", by class "RangedSummarizedExperiment", distance 4
>
> ### ### ### ### ###
>
> getClass("SummarizedExperiment")
> ## Class "SummarizedExperiment" [package "SummarizedExperiment"]
> ##
> ## Slots:
> ##
> ## Name: colData assays NAMES
> elementMetadata metadata
> ## Class: DataFrame Assays_OR_NULL character_OR_NULL
> DataFrame list
> ##
> ## Extends:
> ## Class "RectangularData", directly
> ## Class "Vector", directly
> ## Class "ExpData", directly
> ## Class "Annotated", by class "Vector", distance 2
> ## Class "vector_OR_Vector", by class "Vector", distance 2
> ##
> ## Known Subclasses:
> ## Class "RangedSummarizedExperiment", directly, with explicit coerce
> ## Class "expA", by class "RangedSummarizedExperiment", distance 2,
> with explicit coerce
>
> getClass("expA")
> ## Class "expA" [in ".GlobalEnv"]
> ##
> ## Slots:
> ##
> ## Name: rowRanges colData
> assays
> ## Class: GenomicRanges_OR_GRangesList DataFrame
> Assays_OR_NULL
> ##
> ## Name: NAMES elementMetadata
> metadata
> ## Class: character_OR_NULL DataFrame
> list
> ##
> ## Extends:
> ## Class "RangedSummarizedExperiment", directly
> ## Class "SummarizedExperiment", by class
> "RangedSummarizedExperiment", distance 2, with explicit coerce
> ## Class "RectangularData", by class "RangedSummarizedExperiment", distance 3
> ## Class "Vector", by class "RangedSummarizedExperiment", distance 3
> ## Class "ExpData", by class "RangedSummarizedExperiment", distance 3,
> with explicit coerce
> ## Class "Annotated", by class "RangedSummarizedExperiment", distance 4
> ## Class "vector_OR_Vector", by class "RangedSummarizedExperiment", distance 4
>
> getClass("SingleCellExperiment")
> ## Class "SingleCellExperiment" [package "SingleCellExperiment"]
> ##
> ## Slots:
> ##
> ## Name: int_elementMetadata int_colData
> int_metadata
> ## Class: DataFrame DataFrame
> list
> ##
> ## Name: rowRanges colData
> assays
> ## Class: GenomicRanges_OR_GRangesList DataFrame
> Assays_OR_NULL
> ##
> ## Name: NAMES elementMetadata
> metadata
> ## Class: character_OR_NULL DataFrame
> list
> ##
> ## Extends:
> ## Class "RangedSummarizedExperiment", directly
> ## Class "SummarizedExperiment", by class
> "RangedSummarizedExperiment", distance 2
> ## Class "RectangularData", by class "RangedSummarizedExperiment", distance 3
> ## Class "Vector", by class "RangedSummarizedExperiment", distance 3
> ## Class "Annotated", by class "RangedSummarizedExperiment", distance 4
> ## Class "vector_OR_Vector", by class "RangedSummarizedExperiment", distance 4
>
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