R: Coercing Item Response Data

as.list.itemresp {psychotools} | R Documentation

## Coercing Item Response Data

### Description

Coercing `"itemresp"` data objects to other classes.

### Usage

      ## S3 method for class 'itemresp'
    as.list(x, items = NULL, mscale = TRUE, df = FALSE, ...)

### Arguments

`x` | an object of class `"itemresp"`.
`items` | character, integer, or logical for subsetting the items.
`mscale` | logical. Should the measurement scale labels be used for creating factor levels? If `FALSE`, the values 0, 1, ... are used.
`df` | logical. Should a data frame of factors be returned? If `FALSE`, a plain list of factors is returned.
`...` | currently not used.

### Details

The `as.list` method coerces item response data to a list (or data frame) of factors with factor levels either taken from the `mscale(x)` or as the values 0, 1, ....

The `as.data.frame` method returns a data frame with a single column of class `"itemresp"`.

Furthermore, `as.matrix`, `as.integer`, `as.double` all return a matrix with the item responses coded as values 0, 1, ...

The `as.character` method simply calls `format.itemresp`.

`is.itemresp` can be used to check wether a given object is of class `"itemresp"`.

### See Also

`itemresp`

### Examples

    ## item responses from binary matrix
    x <- cbind(c(1, 0, 1, 0), c(1, 0, 0, 0), c(0, 1, 1, 1))
    xi <- itemresp(x)
    ## change mscale
    mscale(xi) <- c("-", "+")
    xi

    ## coercion to list of factors with levels taken from mscale
    as.list(xi)
    ## same but levels taken as integers 0, 1
    as.list(xi, mscale = FALSE)
    ## only for first two items
    as.list(xi, items = 1:2)
    ## result as data.frame
    as.list(xi, df = TRUE)

    ## data frame with single itemresp column
    as.data.frame(xi)

    ## integer matrix
    as.matrix(xi)

    ## character vector
    as.character(xi)

    ## check class of xi
    is.itemresp(xi)

[Package psychotools version 0.4-2 Index]