Objects of class item are data vectors with additional information
attached to them like “value labels” and “user-defined missing values”
known from software packages like SPSS or Stata.
Usage
## The constructor for objects of class "item"
## more convenient than new("item",...)
## S4 method for signature 'numeric'
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), ...
)
## S4 method for signature 'character'
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), ...
)
## S4 method for signature 'logical'
as.item(x,...)
# x is first coerced to integer,
# arguments in ... are then passed to the "numeric"
# method.
## S4 method for signature 'factor'
as.item(x,...)
## S4 method for signature 'ordered'
as.item(x,...)
## S4 method for signature 'POSIXct'
as.item(x,...)
## S4 method for signature 'double.item'
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), ...
)
## S4 method for signature 'integer.item'
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), ...
)
## S4 method for signature 'character.item'
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), ...
)
## S4 method for signature 'datetime.item'
as.item(x,
labels=NULL, missing.values=NULL,
valid.values=NULL, valid.range=NULL,
value.filter=NULL, measurement=NULL,
annotation=attr(x,"annotation"), ...
)
Arguments
x
for as.item methods,
any atomic vector; for the as.character, as.factor,
as.integer, as.double, a vector with class "item";
for the unique,
summary, str, print, [, and <-
methods, a vector with class labelled.
labels
a named vector of the same mode as x.
missing.values
either a vector of the same mode as x,
or a list with components "values",
vector of the same mode as x (which defines individual missing values)
and "range" a matrix with two rows with
the same mode as x (which defines a range of missing values),
or an object of class "missing.values".
valid.values
either a vector of the same mode as x,
defining those values of x that are to be considered as valid,
or an object of class "valid.values".
valid.range
either a vector of the same mode as x and length 2,
defining a range of valid values of x,
or an object of class "valid.range".
value.filter
an object of class "value.filter", that is, of
classes "missing.values", "valid.values", or "valid.range".
measurement
level of measurement; one of "nominal", "ordinal", "interval", or "ratio".
annotation
a named character vector,
or an object of class "annotation"
...
further arguments, ignored.
See Also
annotationlabelsvalue.filter
Examples
x <- as.item(rep(1:5,4),
labels=c(
"First" = 1,
"Second" = 2,
"Third" = 3,
"Fourth" = 4,
"Don't know" = 5
),
missing.values=5,
annotation = c(
description="test"
))
str(x)
summary(x)
as.numeric(x)
test <- as.item(rep(1:6,2),labels=structure(1:6,
names=letters[1:6]))
test
test == 1
test != 1
test == "a"
test != "a"
test == c("a","z")
test != c("a","z")
test
test
codebook(test)
Test <- as.item(rep(letters[1:6],2),
labels=structure(letters[1:6],
names=LETTERS[1:6]))
Test
Test == "a"
Test != "a"
Test == "A"
Test != "A"
Test == c("a","z")
Test != c("a","z")
Test
Test
as.factor(test)
as.factor(Test)
as.numeric(test)
as.character(test)
as.character(Test)
as.data.frame(test)[[1]]
providing 
.