R: Virtual class "dfm" for a document-feature matrix

dfm-class {quanteda} | R Documentation

## Virtual class "dfm" for a document-feature matrix

### Description

The dfm class of object is a type of Matrix-class object with additional slots, described below. quanteda uses two subclasses of the `dfm` class, depending on whether the object can be represented by a sparse matrix, in which case it is a `dfm` class object, or if dense, then a `dfmDense` object. See Details.

### Usage

    ## S4 method for signature 'dfm'
    t(x)

    ## S4 method for signature 'dfm'
    colSums(x, na.rm = FALSE, dims = 1, ...)

    ## S4 method for signature 'dfm'
    rowSums(x, na.rm = FALSE, dims = 1, ...)

    ## S4 method for signature 'dfm'
    colMeans(x, na.rm = FALSE, dims = 1, ...)

    ## S4 method for signature 'dfm'
    rowMeans(x, na.rm = FALSE, dims = 1, ...)

    ## S4 method for signature 'dfm,numeric'
    Arith(e1, e2)

    ## S4 method for signature 'numeric,dfm'
    Arith(e1, e2)

    ## S4 method for signature 'dfm,index,index,missing'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,index,index,logical'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,missing,missing,missing'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,missing,missing,logical'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,index,missing,missing'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,index,missing,logical'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,missing,index,missing'
    x[i, j, ..., drop = TRUE]

    ## S4 method for signature 'dfm,missing,index,logical'
    x[i, j, ..., drop = TRUE]

### Arguments

`x` | the dfm object
`na.rm` | if `TRUE`, omit missing values (including `NaN`) from the calculations
`dims` | ignored
`...` | additional arguments not used here
`e1` | first quantity in "+" operation for dfm
`e2` | second quantity in "+" operation for dfm
`i` | document names or indices for documents to extract.
`j` | feature names or indices for documents to extract.
`drop_docid` | if `TRUE`, `docid` for documents are removed as the result of extraction.

### Details

The `dfm` class is a virtual class that will contain dgCMatrix-class.

### Slots

`weightTf`

  the type of term frequency weighting applied to the dfm. Default is `"frequency"`, indicating that the values in the cells of the dfm are simple feature counts. To change this, use the `dfm_weight()` method.

`weightFf`

  the type of document frequency weighting applied to the dfm. See `docfreq()`.

`smooth`

  a smoothing parameter, defaults to zero. Can be changed using the `dfm_smooth()` method.

`Dimnames`

  These are inherited from Matrix-class but are named `docs` and `features` respectively.

### See Also

dfm

### Examples

    # dfm subsetting
    dfmat <- dfm(tokens(c("this contains lots of stopwords",
                      "no if, and, or but about it: lots",
                      "and a third document is it"),
                    remove_punct = TRUE))
    dfmat[1:2, ]
    dfmat[1:2, 1:5]

[Package quanteda version 3.1.0 Index]