R: Testing NMF Objects

is.nmf {NMF} | R Documentation

## Testing NMF Objects

### Description

The functions documented here tests different characteristics of NMF objects.

`is.nmf` tests if an object is an NMF model or a class that extends the class NMF.

`hasBasis` tests whether an objects contains a basis matrix – returned by a suitable method `basis` – with at least one row.

`hasBasis` tests whether an objects contains a coefficient matrix – returned by a suitable method `coef` – with at least one column.

`is.partial.nmf` tests whether an NMF model object contains either an empty basis or coefficient matrix. It is a shorcut for `!hasCoef(x) || !hasBasis(x)`.

### Usage

      is.nmf(x)

      is.empty.nmf(x, ...)

      hasBasis(x)

      hasCoef(x)

      is.partial.nmf(x)

      isNMFfit(object, recursive = TRUE)

### Arguments

`x` | an R object. See section Details, for how each function uses this argument.
`...` | extra parameters to allow extension or passed to subsequent calls
`object` | any R object.
`recursive` | if `TRUE` and `object` is a plain list then `isNMFfit` tests each element of the list. Note that the recursive test only applies in the case of lists that are not themselves NMFfit objects, like `NMFfitXn` objects for which the result of `isNMFfit` will always be `TRUE`, although they are list objects (a single logical value).

### Details

`is.nmf` tests if `object` is the name of a class (if a `character` string), or inherits from a class, that extends `NMF`.

`is.empty.nmf` returns `TRUE` if the basis and coefficient matrices of `x` have respectively zero rows and zero columns. It returns `FALSE` otherwise.

In particular, this means that an empty model can still have a non-zero number of basis components, i.e. a factorization rank that is not null. This happens, for example, in the case of NMF models created calling the factory method `nmfModel` with a value only for the factorization rank.

isNMFfit checks if `object` inherits from class `NMFfit` or `NMFfitX`, which are the two types of objects returned by the function `nmf`. If `object` is a plain `list` and `recursive=TRUE`, then the test is performed on each element of the list, and the return value is a logical vector (or a list if `object` is a list of list) of the same length as `object`.

### Value

`isNMFfit` returns a `logical` vector (or a list if `object` is a list of list) of the same length as `object`.

### Note

The function `is.nmf` does some extra work with the namespace as this function needs to return correct results even when called in `.onLoad`. See discussion on r-devel: https://stat.ethz.ch/pipermail/r-devel/2011-June/061357.html

### See Also

`NMFfit`, `NMFfitX`, `NMFfitXn`

### Examples

    #----------
    # is.nmf
    #----------
    # test if an object is an NMF model, i.e. that it implements the NMF interface
    is.nmf(1:4)
    is.nmf('NMFstd')
    is.nmf('NMFblah')
    is.nmf( nmfModel(3) )
    is.nmf( nmf(rmatrix(20,10), 3) )

    #----------
    # is.empty.nmf
    #----------
    # empty model
    is.empty.nmf( nmfModel(3) )
    # non empty models
    is.empty.nmf( nmfModel(3, 10, 0) )
    is.empty.nmf( rnmf(3, 10, 5) )

    #----------
    # isNMFfit
    #----------
    ## Testing results of fits
    # generate a random
    V <- rmatrix(20, 10)

    # single run -- using very low value for maxIter to speed up the example
    res <- nmf(V, 3, maxIter=3L)
    isNMFfit(res)

    # multiple runs - keeping single fit
    resm <- nmf(V, 3, nrun=3, maxIter=3L)
    isNMFfit(resm)

    # multiple runs - keeping all fits
    resM <- nmf(V, 3, nrun=3, .opt='k', maxIter=3L)
    isNMFfit(resM)

    # with a list of results
    isNMFfit(list(res, resm, resM, 'not a result'))
    isNMFfit(list(res, list(resm, resM), 'not a result')) # list of list
    isNMFfit(list(res, resm, resM, 'not a result'), recursive=FALSE)

[Package NMF version 0.20.6 Index]