psychotools (version 0.7-4)

as.list.itemresp: Coercing Item Response Data

Description

Coercing "itemresp" data objects to other classes.

Usage

# S3 method for 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)